Hi Rich, You'll have to find her obituary to know who she was. There is NO guarantee that the Last Residence from the Social Security info REALLY was her last residence. the Soc. Sec. use that field for other purposes.
However, since we don't have any other info (I looked up her death info but only soc. sec. info came up), let's look in Pleasanton and Alameda Co. There are a couple of obituary volunteers in Alameda Co. at freepages.genealogy.rootsweb.ancestry.com/~obitl/volca.html
The 1940 Census has been released to the public but California isn't indexed at this time. Check Census records in a couple of months. It might provide more info about the couple. Successful Searching!