Husband trying to claim a share in sisters property after her death.

Hi, My Sister passed away without a will a year back.She was married without Children at the time of death. She has below property registered on her name. 1.2BHK Flat which was gifted by my mother before marriage while she was studying. 2.Share in Father's ancestral Property. My Brother in law is asking for Succession now and he wants to proceed legally. I have read as per HSA, Hindu Female dying intestate, the source of property will be used for deciding the proper heir. Could you please clarify. 1.Does he have any ownership on Property and Gold etc. 2.How to change the ownership to mother's name or my name