SSDI shows both of these THOMPSONS dying in August 1985:
HOWARD THOMPSON03 Aug 1893 Aug 1985 93940 (Monterey, Monterey, CA) (none specified) 331-07-2993 Illinois SS-5
The only match in California Death Records for a Howard Thompson with the birth/death years you provide is for Howard C. Thompson; the different middle initial could be a transcription error,but the birthplace is given as IOWA (not Illinois) and the mother's maiden name is given as NIELSEN. They are discrepancies from your information, but may have been errors on the part of the "informant"--the person providing the information at the time the death record was made.
THOMPSONHOWARDC mother's maiden NIELSEN born 08/03/1893 IOWA death MONTEREY CO. 08/08/1985 SSN 331-07-2993 92 yrs