Property of deceased person

Hi All, I am very sorry for below lengthy details beacause we are staying in the property for many years and interested to buy the property and i dont have any other option and dont know the advocate also to clarify below details. I am planning to buy one property but owner of the property is deceased and Original sale deed of the property is now in bank locker and bank account is on deseased name. The banker is asking legal heir certificate to open the bank locker. Property owner was a director in a company and was owner for many properties that is the reason there is a dealy to get legal heir certificate. Husband of property owner is having death certificate and family member certificate. I have contacted one person for home loan and he is asking current original sale deed and last linked document should also be original ( sale deed) but all these documents are in a bank locker and banker is asking for legal hier certificate. One person is ready to speed up the process to get legal hier from court. Below are my queries. 1. Death and family member certificate is enough to open bank locker. 2.If above documents are not accepted by banker then legal heir certificate from court is enough to open bank locker. 3.If banker will not accept for any of the above documents then release deed is enough to get home loan. 4.I am not sure but if property doest have approval can wet get BRS now and what will be the amount. Please reply to my above queries Thanks in advance for your valuable answers