Can money given as a gift be taken back ? If yes, how much?

My father has sold his flat and given me 50 lac rupees in cash and cheque. I prepared the gift deed for that and taken his sign in front of two witnesses. Gift deed format is given below. GIFT DEED KNOW ALL MEN BY THESE PRESENTS that I, _____________ S/o Sh.___________ r/o ____________________, transfers voluntarily, CASH OF value of which is Rs.50,00,000 (Rupees 50 lac only) to my SON SRI.____________ S/o of Sh._________________ (hereinafter referred to as "the donee") To Hold the same to the donee absolutely forever. I further declare that the said gift has been made by me out of my natural love and affection for the donee and the same has been accepted by the donee. IN WITNESS WHEREOF, I have executed this deed this ________ day of __________. I purchased the 2 bhk flat using his as well as my money. Now my father is staying with me in the same flat. I spend around 5 lac rupees on his medicine and hospitalization. But now after 3 years he wants his money back and wanted to stay seperate. In this case, how much money should i give him back. Should i give him 50 lac? or should i give him 50 lac minus 5 lac spend on his medicine and hospitalization? or should i give him 50 lac plus interest? Please advice.