This link may help you understand what official documents are needed to file a final return for a deceased family member:
Death in the Family:https://turbotax.intuit.com/tax-tips/family/death-in-the-family/L5albFXM4?srsltid=AfmBOorISn-YRhmbe1oxW-zJpmEH1vkzHmYJopJh7qpSTeVlWw24ChcH
My condolences on the loss of your family member.