Waarisan Certificate

My father had been a State Government Pensioner who expired in 2013 & was drawing his pension from SBI with my mother as nominee. On his expiry we had submitted a letter of notice to the bank informing about his death with a copy of his death Certificate to stop further credits to his pension account. My mother being very unwell was unable to personally visit the bank to complete the necessary formalities for settlement of his accrued dues on his pension account. My mother was also a Central Government Pensioner who expired in August 2020 & was drawing her pension from SBI with my father as nominee. On her expiry I had submitted a letter of notice to the bank also informing about her death with a copy of her death Certificate to stop further credits to her pension account. I had approached SBI for settlement of accrued dues for both my late father & mother. The bank has insisted on a Waarisan Certificate which is to be certified by the local municipality to be submitted. Please advise, if I need to get two separate Waarisan Certificate, one each for my father & mother, or one single Waarisan Certificate for both, from a First Class Magistrate of a District Court which will suffice my purpose at the bank.