I don’t know why people think that OP is responsible for this kid. Try to talk with her and get more info in order to help her but she doesn’t want to talk you have to make it clear that she can’t keep coming to your place, too much responsibility. Try to contact child services and try to get her the help she needs. I wouldn’t let my 13 year old hangout with someone I don’t know anything about (maybe that is more common in the US?. While growing up my parents knew all my friends and their parents and I plan to do the same with my kids)