Looking for Dusek Smith of Northern California

I have found all information on Albert H. Dusek, (grgrandfather) Albert Harry Dusek, (grandfather) and Albert Howard Dusek, (father).
HOWEVER, the first Albert (my great grandfather) seems to be missing a wife. She died between 1897 and 1900. In the 1900 census, Albert is listed as a widower. Looking at the death records of their sons, she is listed as C.SMITH. We have looked in cemeteries in the area where the sons were born. No C. DUSEK or SMITH. We even looked in surrounding towns. The only thing we can think of is, she is in one of the dozen or so "unmarked" graves.