Your sister is old enough to take responsibility for herself and her child, and old enough to know that she has a duty to keep her rented property clean and in good order. I understand your desire to help, but sorting out other peoples' problems for them usually encourages them to sit back and take even less responsibility for themselves. it must be difficult for you having to work with her landlord. Could she be encouraged to give her one last chance if you offer to go and help her clean up the place. The landlord must find it equally embarrassing and uncomfortable working with you in the circumstances so perhaps it's worth a try. If not, I suggest your sister contacts the Social Services dept of her local Council, but they all have long housing lists and are hardly likely to give her priority when she's being evicted for being slovenly. If the landlord isn't prepared to give her another chance, I'd personally keep well out of the situation and let your sister sort it out for herself. She's a big girl now and it's time for her to grow up and act like an adult.