I didn't find anything on Thomas and Fanny Brown Clark. Do you have copies of their obituaries? There are volunteers at Random Acts Genealogical Kindness who will look up obituaries. Go to raogk.org, read guidelines, choose California, choose Sacramento Co and choose one volunteer.
I didn't find anything on Percy and Mary Schandoney Clark either.
Did Ida and James Dempsy have children? I found an Ida and Wanda Dempsey in 1900 living in Oakland Ward 4, Alameda Co., CA.
Andrew Pool, head household, b. CA Feb 1855, brakeman railroad.
Ida Dempsey, sislaw, b. CA Aug 1845, divorced. [notice that the death date is very different from your Idah.]
Wanda T. Dempsey, niece, b. CA May 1897.
Clifford A. Pool, son, b. CA Sept. 1887.
Charles A. Pool, son, b. CA Aug 1890.
Clarence Pool, son, b. CA Aug 1893.
Thomas G. Clark, grandfather, b. england July 1842, widow. [Thomas is another reason I'm asking you about this family group.]
I also found Ida Williams and family and this Ida's birth date is close to yours.
In 1910 Ida and family were living in Oakland Ward 2, Alameda Co., CA.
David W. Williams, b. Wales, 54, M2 1 yr, immigrated 1858, naturalized before 1910 Census, janitor mason _____.
Ida, wife, b. CA, 38, both parents born England, M2 1 yr.
Wanda I. Williams, b. CA, 12.
Edward R. Williams, b. CA, 23, single, teamster trucking co. [David's son from previous marriage.]
In 1920 Ida and Wanda were living in Oakland, Alameda Co., CA.
Ida Williams, b. CA, 47, both parents born England, widow.
Wanda D., dau, b. CA, 22, single, music teacher.
In 1930 Ida was living in Oakland, Alameda Co.
Ivan L. Bigler, b. OH 37, marr @ 29, accountant shell oil co.
Wanda W., wife, b. cA, 32, marr @ 24, father born-England, mother born-CA.
Ida Williams, motherlaw, b. CA, 58, widow.
You must have the Census info for Edwin C. Clark. I'd look for his daughters, Florence and Myrtle's marriage info in Placer or Sacramento Counties. You'll need a volunteer to do this for you. I'd find them through RAOGK.
In 1930 Edwin T. Clark (son) was living in Willow Glen, Santa Clara Co., CA.
Edwin T. Clark, b. CA 27, marr @ 22, both parents born CA, bookkeeper fruit packing.
Florence W., wife, b. CA, 22, marr @ 18.
An Edwin Clark born 9 Sept. 1903, Last Residence Rosemead, Los Angeles Co. died April 1974. His social sec. # was assigned in CA before 1951. Source: Social Security Death Index.
I'd find a volunteer at RAOGK and request a copy of his obituary. Hopefully it will provide enough info to verify if he was Edwin's son. Successful Searching!