There is a lady in our society who always threatens her father and mother-in-law saying if they do n

There is a lady in our society who always threatens her father and mother-in-law saying if they do not listen to her then she and her parents will file a dowry case against them. These old people are very decent and don't know what to do. Every other day she creates a scene and starts threatening them. Due to this they are mentally disturbed. What can be done in this case?