Poor kitti(es)! It sounds as if these people don't have a clue about cats. Yes, you should definately take that kitty, she'll be far better off in your home. You should also have her checked at the vets, UTI can be a serious matter, and she definately needs to be treated for the earmites!!

If you can get any leaflets about cats care, I think it's a good idea to give them to these people. Or print some articles from the net.

Best of luck with her!