How to get the house transferred in my name and mothers name

I stay with my mother in a pagdi flat. The house is in the name of my grandfather who is no more. My grandmother is dead. My mother is the only daughter of her parents. My mother has two children. My sister is married & stays with her husband. I want the house to be transferred in the joint names of my mother & her son myself. I have got the NOC from my sister to effect the house transfer. I have spoken to landlord & he demands money for the transfer. Should I pay the money for the house transfer. Is it possible for me to transfer the house in my name directly – the son ? What is the procedure for the house transfer ? Do I have to ensure the transfer of property is recorded in Government records ?