Then ask the court for custody of the children and don't allow her to return to your home. If you refuse to house her anymore, she becomes an indigent unwed mother and perhaps the Salvation Army will look after her as a destitute case. If she's just a naughty child living with her family, then you have to take her into your own hands and treat her as such. Make rules and demand that she obey with the threat of getting police if she doesn't. If she is a selfish woman making her own decisions, unconcerned with anyone else or even her own wellbeing, then ask her to get a job and go and live elsewhere.
Nothing seems to be very pleasant, does it.
If such a thing as this would ever happen, you might have to face the eventuality of losing the grandchildren, but that could be the best of all solutions. Supposing your daughter eventually assumes some decent adult behaviour and decides to become a good mother. She has your example to follow and miracles do happen. Or suppose that from this moment on you set your mind to teaching her some of the things she needs to know to look after her children now, and through the years to come. The situation you are in now seems like a hopeless trap with no way out, but I think you might find one.