What are the rights on property in the name of parents?

Hi, I have a joint family. I am married and need to clear a few doubts about the right of my parents who are living in the house on my grand mother's name. The situation is such that my grandfather had the plot in his name and my elder uncle contributed some amount in the construciton of the the house. After my grandfather passsed away, the house was moved to my grandmother's name after all her children (5) signed the agreement of no objection. Please note my grandparents have 5 children, 3 sons and 2 daughters. Two sons (both my uncles) live in HOLLAND since past 36 years and have the citizenship. One Aunt is married and another is not and stays with us. My dad is in India. My house has 3 floors. My parents and brother live on the ground floor, my grandmother and aunt(who is unwamrried) stays on the second floor and the thrid floor is on rent, the money of the rent is given to my grandmother. Now, my grandmother and elder uncle keep harassing my parents to leave the house. They say they have no right to stay there. My parents are staying in this house since 30 years. My grandmother says she can do whatever she wants and says she will give the top floor to my elder uncle, the second floor to my unmarried aunt and the ground floor to my dad, uncle and another aunt. I want to know does she have the right to harass my parents and ask them to leave? also, if my parents are staying on the ground floor since last 30 years and have invested in the interioirs/repairing/maintenance, what is their right ? Thanks. Regards Neeharika