"Ive never stayed with them. We live in a tourist area so thats why they've come. They asked to come."
How well do you actually KNOW them? You do know you are perfectly within your rights to say "no"? People who live in tourist areas are prime targets for certain types of cheeky fuckers!
My dad was army and a couple of times we came to be living in very popular tourist areas. After the first one (which was also close to a VERY well known sports venue) my parents learned the hard way not to be too accommodating to the family and friends who were not usual visitors...but all of a sudden keen to visit when we were living somewhere people like to holiday!
It's a pisstake!
If they're REALLY friends they will not be at all offended by your raising the issue of your tight budget and being honest with them.
If they're NOT really your friends then who gives a fuck if you offend them?!
So you have nothing to lose by being honest.
I'm also a single mum, we've never had spare money really but I've hosted certain people as visitors, not once have I HAD to say to them to contribute to costs, they've at the very least covered their own costs and some have even very kindly paid for takeaways/meals out for dd and I too as a thank you (which I did not accept instantly, they were quite insistent and I was very grateful for it and said so), one even sneakily topped up my meter before leaving and refused to take a penny in payment back, she'd been a single mum herself and remembered how tough it was, was by this point much better off and said as far as she was concerned it was a very cheap rent for a lovely week spent staying with us. Will never forget that and have (hopefully) repaid her kindness in other ways.
All those giving it "I'd never expect guests to pay" I'm guessing you've never been on a very tight budget where paying for guests could well mean you needing to miss a meal (or several) in the week/month after they leave? Aren't you lucky that you've never NEEDED guests to pay?
"I don’t buy that friends wouldn’t know that a single mother wasn’t rolling in money." I don't buy that anyone with half an ounce of common sense wouldn't even consider that suddenly having to cater for 4 extra people can be difficult for quite a lot of people right now!
I'd lay odds these cheeky gits didn't even do the dishes!