Neighbor wants the guy out, but since she lets her worthless son live in the house, and the guy was invited by the son, it's debatable what recourse she would have. She's already suffered a heart attack due to the stress caused by the son.
Does she have sufficient means to live without that house?
If so, then forgive, forget and move on.
Write the kid out of the will and simply donate the house to him today, right now.
Its his life, his problems and it will be his house, too.
And, assuming he can pay the taxes and insurance and all the rest, then he can keep it. If not? Another lesson.
This way she is free from him, free from the house, free from the stress and free from all the rest, too.
Win with generosity!
Turn off the utilities and take a long vacation.