Tenant Overstaying, wont vacate

My Father owns an apartment in Bhopal (B-105) which used to be vacant, while we are staying in Bangalore. Our neighbor apartment owner (B-104) in Bhopal had requested my father for a favor to move in to our apartment for 2-3 months, in lieu of a nominal rent payout, since they were renovating their apartment space B-104. My father agreed because he is a good person and likes to help people, especially neighbors. Hence the said neighbor has been staying with no rent agreement, and now is refusing to go back to his apartment even after 6-7 months of staying by giving one or the other excuse. We stay in Bangalore and my father is a senior citizen and cannot travel to bhopal to sort this issue and hence he is taking advantage of the fact that my father is a senior citizen. Please advice what legal course we should take on this.