Tenant refusing to vacate House

Hi, There is in a small town called Munger in Bihar, where my grandmother had a tiled house of 3 rooms constructed in a land of 5 Katha. She rented it to a poor lady on a very minimal amount long back may be 40 yrs back or more.That lady passed away and his brother became the renter and he lived with his family in the tiled house. They were poor and sometimes they paid rent & sometimes they could not. Meanwhile my Grandmother passed away. The sons of brother started earning and they did some small renovation without our permission/information of 1 room when he got married. Mostly they did some basic maintenance of house without informing us or taking our permission. Since the rent was so minimum they were happy maintaining it at their cost and we never bothered about these small things. They paid rent ( 500 approx )to my grandmother first & then to some relatives in cash who lived in the same town meanwhile we lived in Patna. Since they were poor, honest people and very friendly with my father and the relatives of father who lived in Munger, we never troubled them with any thing. Meanwhile my father passed away in 2011 and the brother of the lady passed away 2-3 yrs after that. FYI: The land is gifted to my Dad on a white paper and two sisters of my Dad don't claim it. Now the rent was increased by my Mom to 1000 per month and the son of the brother had a verbal agreement with mom that he will pay rent on time and will be new renter. Now in 2015 rent was increased to 1500 per month and was asked to pay online to my Icici bank account. He paid rent for 2 yrs approx bi-monthly 3000 for 2 months deposited by cash in my account in Munger Branch of Icici. Reason being asked to transfer online was because cash given to my relatives were not handed over to us in full and some times they also spent it because they were poor and some times hard pressed for money. Now Jan 2019, I went to the that son and asked him to not make any renovation in the house because we will demolish everything and make a new home on that land then I noticed he is considering himself the owner of the house. He said he will not vacate and stopped paying rent. We tried to convince them to vacate for 6 months by our relatives who have good terms with them but it seems it is not working and the guy is now demanding money from us. FYI: We have always Paid Municipality tax of the house and we have receipts of the taxes paid since we bought the house. Initially the tax was less as the lady & his brother always said we are relatives but during inspection few yrs back the son said said we are renters here and the tax was increased. I need help to understand my legal option to get the premise vacated asap. I am a working professional in Hyderabad and its costly to take leaves and travel to Munger again & again. Thanks & Regards Kashif