Nancy's Elusive Grandmother

Many thanks to the responses from George, Patty, & Alicia.
Unfortunately your advice doesn't work because my grandmother's
married name (I think) was Blanche, but maybe Blanco. In
a death certificate for a daughter, she used Marquez, and
in another document she used Duval as surnames. I have searched
all these names. She told my father he was born in Ca. but he
couldn't find his BC in Sacramento. There are absolutely no records
available, be they baptismal, marriage, or ? I truly believe my
grandmother deliberately did not want to be found. So, my hope is
someone can help identify and tie her to the Guerrero family in the
photograph. From that one clue, Jesus Sanchez Guerrero and the
1930 Mexico census I have learned that this family has a very
important background in Guadalajara history. I think my grandmother
had something to hide from them, but left me with this mystery as
to who I really am. As I mentioned before, maybe Francisco Sanchez
Guerrero is my grandmother's father, but I haven't found a marriage
certificate for him in Guadalajara which could lead me to a family.