Take special note that you will not be able to e-file the return. This is because I am confident that by now, the IRS has her SSN locked, so that it can't be used fraudulently. If you attempt to e-file, the most common error you will receive is "SSN LOCKED", but it could be any number of other errors too.
So you will need to sign and mail the return to the IRS. If you are the legally authorized representative of her estate, you may (or may not) also need to include in your mailing, documentation that proves it.
