Transfer of immovable property & mutation

Hi,

My father died recently leaving his behind property registered in his name. We want to transfer the property to my mother name. What is the procedure for it.

I have mother,brother and grandmother. Is grandmother a legal hier and does her sign are needed for the transfer of the property.

Further, the property is of DDA and we want to do the mutation also. What would be the procedure for the same.

Thanks,

Amit