You'll need to go to a local Social Security office with several documents. You'll probably need to set up a meeting in person with them. Here's a guess at documents you'll need: official death certificates for your father; documentation regarding your mother's inability to come to an in-person meeting (from the medical institution or her physician?); power of attorney for you to handle their business; likely your birth certificate or adoption papers for you. I strongly urge you to not estimate this information unless you are certain that the amounts did not change year-to-year or that you can track the COLA adjustment for 2023-2024. At this late date, you might be advised to file an extension or make an estimated payment now and file for the extension.
