Tulip, you have my sympathy. I have a friend hosting who is in a similar position - all her attempts to find solutions apart from the one that is most inconvenient for her are met with a flat "no" and she's exhausted from the effort of essentially parenting another whole family.
I totally get the temptation to help as much as we possibly can, because many (not all) of those arriving here have so little left and we have so much, but I'm realising that I have to have boundaries and that I need to stick to them. And also that it's ok to say "you know, this was something I was willing to do but now it needs to change".
The expectation was that we would provide safe accommodation for our guests, and that anything else is up to us and a bonus. I've heard lots of stories like yours, where hosts are struggling to meet the demands of their guests, but in the medium term they are all going to need to be independent and to live like the rest of us do, as far as possible. And I'm sure lots of people would love to be driven everywhere, but that isn't possible so we compromise - on time, on doing something we don't enjoy, on getting wet. It's just life. So it's an uncomfortable conversation but
I've been extremely lucky as my guest is independent and keen to do as much as possible for herself. And I realise it's easy to write this stuff and hard to put into practice - I'm terrible at it. If I had good robust boundaries and was able to say "no", I probably wouldn't have signed up for this in the first place.
Probably not helpful. Mostly, I just want to say you're doing a good thing. Hang on in there.