Sister in law and mother harassing for property

We have own house. My husband is having sister & Mother. Both are very dominating and greedy people. Both has raised their hands many times to my husband for one or the other things. That own house is in my father in law's name. He is expired last year. They may threaten my husband to bill the property to her name. My husband is very very innocent. In my absence if they threaten him what to do. what is the solution for this.