On the deat certificate for Susan Brown, her mother's name was Lydia Johnson. This looks like it might be Susan's mother and sister, but there's no sign of Susan.
1880 United States Federal Census Belle Rivier, Assumption Parish, Louisiana Sylvie Johnson b f 50 widow born LA fborn Guinea? mborn Virginia servant Leanda Flander mu f 14 dau born LA fborn NY mborn LA at home (living next door) Joseph Kittredge w m 47 md born LA fborn NH mborn MS? Mary Kittredge w f 36 wife md born VA fborn VA mborn VA keeping house Ivy Kittredge w m 9 son born LA fborn LA mborn VA Willogby Kittredge w m 7 son born LA fborn LA mborn VA Olivia Kittredge w f 5 dau born LA fborn LA mborn VA
This may be Susan, a servant in the J. B. Whittengton household. Edmund Johnson may be a half-brother to Susan and Leanda.
1880 United States Federal Census Assumption, Louisiana J. B. Whittengton 44 w m father md born LA fborn MD mborn LA notary public M. Ann Whittengton 39 w f mother md born LA fborn NH mborn IL painting? Joseph Eaton Whittengton 16 w m son born LA fborn LA mborn LA at school Harry Whittengton 13 w m son born LA fborn LA mborn LA at school Mary Louise Whittengton 11 w f dau born LA fborn LA mborn LA at school Bessie Whittengton 7 w f dau born LA fborn LA mborn LA at school Marion Whittengton 5 w f dau born LA fborn LA mborn LA Edmund Johnson 12 b m servant born LA fborn LA mborn LA servant Susan Flanders 15 b f servant born LA fborn LA mborn LA servant Julia Pike 24 w f teacher born LA fborn NH mborn KY teacher