New tenant asking me to return the security deposit

I was living in a flat, sharing it with other 2 boys. It is a 2 bhk flat I was sharing the master bedroom while other boys were sharing other room and hall respectively. Before vacating the flat, every one has to find a replacement for their rooms, I did the same. There was another condition that I had to share the bathroom with another boy. I found a replacement Mr X he shifted after I vacated and he transferred rent as well as security deposit to me. Now that new guy had some quarrel with the current guyz living and is aksing me return the deposit and threatening to file a case against me