Succession certificate

My mother expired in May 2015 during a visit to Hyderabad. My father expired in 2012. My sister expired in September 2015. She had no children. My mother's bank asked for succession certificate to transfer her assets. I was issued succession certificate by district court in Saket, New Delhi in Dec 2015 and received assets. Now my sister's husband has filed for succession certificate in Hyderabad claiming that my sister was my mother's legal heir and he is her legal heir. My mother stayed in Delhi and filed her income tax return also from here. All her assets are also in bank account in Delhi. I have not received any summons or notice from court in Hyderabad. Only the bank has been asked for details confirming my mother's assets. What should I do?