What are the rights of Father-in-law and Mother-in-law?

There is an old retired couple (retired from govt service). Their son died 1.5 years ago. Their son and his family lived on the first floor of their home. The son had two businesses (transport business and one govt contract for 3 years) and both of these businesses have been transferred to his wife. All his properties (2 plots, 1 car, policies, investments) have been transferred into his wife's name. The son's wife is not in good terms with the in-laws and says she does not want any contacts with them. But here is the problem: She still lives on the first floor of their home with her 2 kids and wants that home to be transferred in her name. The home was built by the father and mother's hard earned money and they are still giving EMI for it after 30 years. They took a loan during their govt service. The son's wife has many times abused them in public and never talks to them. Now, the father and mother-in-law want to sell out that home to get rid of their daughter in law.