To tell my MIL if she wants a son to name she can go have one and not be engrossed on what I choose to name my son.

I don't believe she does hate the MIL. I believe she's frustrated at the MIL not reverting to type and ignoring her grandchild and getting in the way of a recent PP mother from getting on with learning how to look after her child.

What a pathetic old cunt.

I think choosing two names from your side of the family and none from DH is a bit insensitive to be fair. MIL shouldn’t keep talking about it but it would have been more thoughtful of you to consider a name from DH side as a second name or just a neutral name. This smacks of your family being more important than DHs and something I see quite often.
You’re not unreasonable to choose names you like but I understand why she feels hurt.

Totally should be you and your husband to choose names and it is nothing to do with anyone else.
I am a mil, I would never say I disliked a name either, not my business.
As for the daily visiting, tell your husband to tell her you need some days alone, this is not rude to say.
Its great your husband has 3 months off, you should be enjoying visitors on your terms. It’s your first baby, make the most of it.

Just admit you hate your MIL (which may or may not be justified). I think the name saga is a red herring.
Have to say that double barrel names are really chavvy not to mention completely unnecessary if you're married.

Not really. My aunt just had her first grandson recently. She has a great relationship with her daughter in law and sees her grandchild regularly. She actually, arguably, has a closer relationship with parents than they do with the wife's mother precisely because she doesn't feel the need to nitpick their every decision...repeatedly.
Mothers of boys are welcome to have an opinion. Doesn't mean that they should go on expressing it until everyone drops everything to accommodate them. Same goes for mothers of girls. An appropriate advice for most people, really.

People are so precious and weird, as fucks, with their children's names. I remember asking my dm why this name was chosen for me, like who was I named after. She said 'no idea, could not care less, I was so grateful to God you came out alive, I came out alive out of this, I did not care'. She does not even remember who went to the registry office to get the certificate, she was so ill for a while, my dad, my grandparents or some other relative, so that person must have come up with the name for me.

You can say no, OP.

My PIL saw DS1 when. he was two days old and not again until he was five weeks old. Ok, we live eighty miles apart, but if we lived one mile apart I would not have had them round daily.

One of my children has three Christian names - all of them are from my side of the family. Nobody cared about it. We both liked the names better.

You are contradicting yourself there a bit. You say she doesn't like you but wants yo have a close girly relationship with you... I think its just that you don't like her so just admit it and move on.

The better tactic would have been to calmly say that this is the name you and your husband picked out together. Your MIL is blaming you for the baby not having a name from their side of the family, but that was a mutual decision, and that needs to be pointed out.

Telling a presumably post-menopausal woman that if she wants to have a baby, she can have one herself, was nasty. Saying that she had a chance to name her children, and this is your chance to name yours, would have gotten that point across without sounding like you were taunting her for being an older woman.

My husband and I didn’t give our children the names of any relatives so we wouldn’t have this kind of situation, but my MIL was still unhappy. We had girls, but our prospective boy name was – let’s say it was “Jonathan George.” She wanted to know if “Jonathan” was in honor of the priest who baptized my husband, which neither of us had thought of, and that disappointed her. My dad, and my husband’s late uncle/godfather, are both named “Henry,” and she wanted to know why we weren’t considering “Jonathan Henry.”

I don't think the OP is pretending to worry.
I get the feeling she quite enjoys being unpleasant to her MIL.

Contaminate is such a strange choice of word.

I can understand you feeling a bit claustrophobic, I wouldn’t want my MIL visiting every single day either.

But “contaminating the baby” is a really weird thought process.

Wait until he’s all grown up and his partner thinks she’s got the MIL from hell, it’ll come sooner than you think.

Honestly, yes, she's in the wrong here but your attitude absolutely stinks

This

It sounds like you were both rude. But you have more of an excuse due to being a new mum. I was similarly rude to my MIL when she kept pressurising us to have our baby baptised. I eventually just snapped back, after a pretty constant barrage. I do understand a little bit why she’s miffed. She’s feeling emotional - and territorial - about her new grandson and probably thinks you should have been more even handed in choosing the forenames (not saying I agree - my youngest is named after my late dad!) But she should have kept her trap shut. People can feel anything they like, with or without good cause, but saying it out loud and, worse still, harassing you about it, is absolutely not acceptable. The phrase ‘keep your counsel’ springs to mind.

I wonder why you started this thread, really. You don’t like her, she’s a pain in the backside who the rest of the family seem to dislike, too. Why are you pretending to worry about whether you’ve offended her or not? Don’t you have better things to do with a newborn needing your attention?

There was never even a slight chance that our son would be named after anyone in my husband's family. He and I both agree that they had abysmal taste in names for the most part. We would have been choosing from Horace, Ronald, Dennis, Anthony, Sidney and Albert (the only one I would even have considered). As it was, both my PIL had died before we had children, he's an only child and not close to anyone else in the family, so that was that. It could be argued that both our children have names from my side of the family but as we chose classic names in both cases so do hundreds of thousands of others in the UK.

So your child has your father and grandfathers name, what about your husbands side of the family? She probably shouldn’t have said anything, but it’s sad you haven’t honoured both sides of the family

Also why is mil mad and not fil?

It’s a son not a daughter so it was never going to have a name from mil or her mother.

She’s what offended on her husband behalf? Or her dad’s behalf.

It would make a bit more sense if op had a girl and named her ops mum, ops granny, ops surname, husband’s surname.

Then yeah I get her nose being a bit put out but still she should keep it to her self or at most maybe one sob to her son I guess. But the child’s a boy given boy names.