I have a copy of the 1880 census record for Alcorn County Mississippi and shows Sarah to be 37 yoa, two years older than Joseph. Sarah was born in Alabama. Her parents were born in Virginia. Sarah was probably buried in Alcorn County Mississippi. Alcorn Co. Mississippi may have a Death Certificate or know where she is buried.
Sarah must have died young because the 1910 census record for Faulkner County Arkansas shows Ada (35) as wife to Joseph (65) for 20 years. Sarah evidently died before 1890.