Who is absolute owner

My father in law purchased a land in 1984 in my mother in law’s name and built a two storey house by taking home loan. He died in 1995 without a will. My mother in law has two sons. Elder one has built 3rd floor and staying with his family for many years and mother in law staying in 2nd floor alone. Younger one has to stay in another city due to job location with family. There are three tenants staying with their families and giving rent to elder son. Elder son does not want give share in the property and has bad relationship with mother in law. He is taking advantage of brother being in another city and can’t come too often due to job responsibilities. Mother in law gifted the whole property to younger son Through gift deed few days back because in any case elder son was not even willing to talk or negotiate. According to him mother in law is not owner because she was not working but many lawyers suggested younger son that she is the absolute owner. Now he is going to file case against gift deed given by mother in law and not vacating house and continue to take rent from tenants.pls respectable lawyers give your valuable advice