His death certificate is on line at sos.mo.gov/archives/deathcertificates. He also died in 1942 and is buried in Holt Summit MO. She is listed as the informant. I found it by entering just "John Thornton." There is no death certificate on the site for her--presumably she died after 1961 (the last year listed). On his death certificate her age is given as 55. Unless she remarried, she's probably buried in the same place. I doubt that Holt Summit has a huge number of cemeteries. Good luck!