Second, you can also go to court. Civil or criminal proceedings can be conducted. But just like calling the police, the court will support you only if the evidence is sufficient. Then at most, I will apologize and pay some compensation for mental damage, which will not have too serious consequences.
Finally, I think, as the old saying goes, a clever woman can't cook without rice, and her grandson is not a psychopath, and she will start work on an old man who should be respected for no reason; The old man is not as miserable as you described. Although he is ill all the year round, I guess he is also a person with a bad attitude. Only young people can't stand it.