I do not have access to Alameda County papers so I cannot help you with an obit, however the CA Death Indexsays that Whipple Spear Hall was born in CA Jan. 12, 1882 and died July 20, 1942 Alameda Co., Ca. Mother's maiden name was Spear.
Eugene Ely also died in Alameda Co. - age 74, on Aug. 30, 1924.
I did not see Mabel Ely on the CADI.
You were right about her marriage. E. B. Ely, native of Iowa, age 27, resident of San Francisco and Mable E. Hall, native of California, age 17, resident of Corte Madera, with consent of mother were married August 7, 1907 in San Rafael by M. J. Walsh, assistant pastor St. Raphael's Church. Witnesses to the marriage were Frank E. Seaton of Corte Madera and Marion Hall of San Mateo.
The license was issued the same day as the marriage took place, so my guess is that the mother was also the witness. The certificate didn't say.
The above information is recorded in Marin County, CA Marriage Book O, page 219.