On April 26, 1868 Mustin married the former Mary Elizabeth "Mollie" Gardner in Carrollton. They had five children: Blanche, Annette, James, Gertrude and one other. Mollie died in 1883 and Mustin subsequently wed Mamie C. Williams in Pickens County on August 19, 1884. His youngest daughter, Gertrude, married surgeon William Elias B. Davis in 1897.
Mustin died in 1895 and is buried at the Friendship Cemetery in Columbus, Mississippi.
- Robert Wilson Davis at Findagrave.com