Clarification on tenant refusing to vacant the room

property law: My Father has rented his room to a couple 3 years ago.initially they used to give rent on time but after 3-4 months they started giving rent irregular with convincing some financial reason. my father requested them to vacant the room but the man used to ask his wife to handle a call and then again she used to give false promises of paying rent next month. because of her behavior my dad got fed up n asked her to vacant room . now she is denying to vacant the room and also stopped paying the rent & electricity bill as well. since 1 year she is not paying single penny when my dad asked her about it then she threaten him by taking the local politicians name. Also from other we came to know that currently she is been indulging in prostitution in room. pls. help me. i cant see my dad in tension. As it is kind a slum area my father did not make any agreement.