Or are you trying to get her 1099 form for SS so you can file taxes. That usually is not ready until February. Since she is deceased I don't know where it will be sent. Is anyone still at her old address?
I was wondering what kind of taxes would require SS forms. I can't remember using anything except the SSN's when doing taxes of any kind. Is the reason you are getting the form is to get the SSN? If you have her Medicare card, it will have her SSN on it.