I found a Fred F. Springer in 1938
Residence: 282 Oxford B., Oakland, CA
Spouse: Nlnelta P. Springer
Source: Polk's Oakland City Directory
I looked for his death info in Ancestry, FamilySearch and findagrave.com but didn't find it.
You might want to contact the California Genealogical Society & Library, http://californiaancestors.org/index.php?opti
... which is located in oakland. They have a 350,000 name database and will do inquiries for $10.
Also ask them if they have a copy of the California Death Index and will they do a lookup in it. It's supposed to be in Ancestry too but I have the feeling that not all of the records were loaded.
Was Fred mentioned in Ninetta's obituary?