Hi Jacob, I checked Ancestry and FamilySearch in Iowa and California under Thorn and Phelan and didn't find her in any location. The most recent Census that is available now is the 1930 Census. The 1940 Census will be available in about one year.
I suggest you find a copy of her obituary. You can contact the Stockton-San Joaquin Co. Public Library, www.stockton.lib.ca.us/ and ask if they look up obituaries and provide electronic or paper copies.
You can also contact the San Joaquin Genealogical Society, rootsweb.ancestry.com/~sjgs/index.htm and ask them too. Successful Searching!