Have you tried ordering his death certificate from the state archives? Burial places weren't always listed on older certificates, but they sometimes were.
Would this be him?
Mouton Carter died 5/10/1938 at age 83 in Ascension Parish
If so, you would need Page: 5503 Volume: 13 of the 1938 statewide death records.
You previously listed Fanny's date of death as 3/5/1920. According to the state death index, her name is listed as Fanny Moore Wallace. If you want to order her certificate, you'd need Page: 2310 Volume: 6 of the 1920 statewide death records.