What does he do to protect himself and prevent her from coming here? How can this woman claim residency? What are his rights?

I am explaining this for a friend out of concern for him, he is a disabled senior. He allowed someone to come to his home, that he owns, a few days a week for a couple of weeks to get rid of storage she had left here some time ago. She did spend the night on those occasions to his objections. She violated that brief OK and was told to leave over and over. She refused and threatened to sue for residency. She is not a roommate, she has not paid any money, has no key, no lease. She has no room here. Her mail was sent here without permission and is now being returned to sender. jThis has been going on since the end of October.