is this a bit rude? Or just me?

This.

If you are asking them whether they are staying, it means that you would have fed them. So a plain 'no' was rude. A 'no, thank you', would have been the correct response.

This was my thoughts, especially if any of them are ND. As far as they are concerned they answered the question.

As for walking out and not saying thank you for having them stay, I've noticed as my childrens friends got older, living on their own at uni etc they stopped saying it.
They wouldn't be saying to each other at uni so maybe in their minds they've stayed at your dd's house, not yours?

I came in, said hello, nice to see you again etc, to which they just replied "Hi". Then I asked if anyone was staying for tea? And they both literally just said "no".

That doesn’t sound like an invitation to me. They could have interpreted it as you meaning “oh, fuck, is that more mouths to feed then??” and/or felt it would have been presumptuous to interpret the question as an invitation.

Their lack of response to your next question was rude though.

Cheeky sods. Good manners cost you nothing and take you far!

They might have meant 'No, your daughter has not invited us.' It might have been a tricky situation for them if they thought that she didn't want them to stay.

Absolutely uncouth, and NOT normal.
They wouldn't be staying lots in my house and I wouldn't ever offer a meal again.
I would be telling your daughter she can be "just how she is" in someone else's space.
Disappointing that your own daughter doesn't realise just how rude her friends are. My children would know that.
Definitely worth a conversation as you certainly don't her showing herself up in a similar manner.
Don't doubt yourself OP

Oh please just give it up.

In French, “merci” can mean no thank you in certain contexts e.g when you are being offered something. Easy to get caught out if you actually want what is being offered!

Exactly, OP didn't offer them something or do something for them, she asked a question. The answer was 'no'.

But then the OP said “ok, well you're both very welcome to stay in you'd like to." and was met with silence. Don’t you think that was rude?

How do you know? They may have meant it, but when you replied “yes, thank you” were too polite to say actually, I meant please buggef off.

Why? Thank you for what exactly if it wasn’t an invitation?

This situation does not indicate anyone being brought up with no manners. If they had been invited to stay, yes, a “thank you” would have been expected, but it wasn’t an invitation. If they had say “thank you” to other people asking the same question, I could imagine they would be met with “that wasn’t an invitation”. To me, it sounds like a hint to go or someone wanting to know if they have to go to the trouble of scraping up two extra portions. Just a simple change to “would you like to stay for tea?” Would have made it clearer all round. Honestly, some of the comments here about “elaborate excuses”. It’s not an excuse, just an explanation of the difference between an invitation and a general question.

Know what is rude?

Your response.

Patronising much?

Are they British, some cultures don't use thank you after saying no?

' That's fine- we're eating in 20 mins though so start wrapping whatever you're doing up and making your way home'

FFS seconded.

Oh FFS 🙄😆😆

Another option: they thought you were being rude by phrasing the question like they were primary school children. Given local variations in meanings of tea/dinner/supper, that specific phrasing of "staying for tea" might have meant staying for a meal much earlier than most adults like to eat, to them.

Or they might just have no manners.

I hope that I never came across as that when I offered my perspective and I certainly don't expect people to just know stuff that I was taught, when I myself am found lacking in many areas.

For example, I had no idea that thank you notes were a thing until I read it on here once. I was telling my mum and she said that she was made to do this by her foster parents in the 60's - she never passed this on to me. And I don't remember ever receiving any neither.

But, I will say that once I have learned something whether it's on here or tiktok, then think 'wow another thing that I never considered before, and now I know' and do with that what I will.

It is so irritating to have neurodiversity offered up as an excuse for being mannerless.
It is almost as bad as saying poor people may have to steal in cost of living crisis.

Both highly insulting to neuro diverse and poor people

I have been very poor and my moral compass nor that of my parents did not switch to allow us to steal. It's a thing called self respect and poverty doesn't erode it.
My sister is neurodiverse and she would not allow that to be an excuse for being mannerless.

Poverty and neuro diverse conditions do not mean that people have to be excused, apologised for, patronisingly 'understood' as if they were a puppy pissing on a rug and they can't help it.

Mrs. Carson 'Yes I'd have probably said, No I'm heading home, or No I have plans'

If you are answering my question, that's a 'No, I would have probably said...' not yes!

ScarlettSunset I'm not going to continue arguing with you - it derails the thread OK you are autistic - they were not!

Your response " you are welcome ........" was incorrect. You should have said one of the following:-
I beg your pardon.
No?....
No what?
Don't be so rude
Where are your manners?
DD if your friends can't be civil, they are not welcome here. Please ask them to leave. (This to be said in front of said friends)
You get the drift?