Molly Thavenet was raised in Providence, Rhode Island, and worked as a secretary at Narragansett Electric Company in Waverly, Rhode Island, before enlisting in the Women's Auxiliary Army Corps (WAAC). Thavenet reported for basic training on 4 June 1943 at Fort Devens, Massachusetts, and then was assigned to the 162nd WAC Headquarters Company, 4th WAC Transportation Company at Fort Oglethorpe, Georgia.
In November 1943, Thavenet was transferred to Naples, Italy, as a stenographer to the Adjutant General Personnel Section of the Production Base Support (AGPBS). In April 1944, Thavenet was transferred to the 6720 WAC Headquarters Platoon with the 15th Army Air Force in Bari, Italy, where she worked with the reassignments of combat crews.
After returning to the United States in October 1945, Thavenet was discharged from the Women's Army Corps with the rank of sergeant, and moved to Providence, Rhode Island.