I can see the rest of the family in 1881:
RG11/844/104/15
26 Castlegate, Richmond, Surrey
Homan, John Head M 67 b Epping Forest, Essex
Homan, Helen Wife F 57 Laundress b Richmond, Surrey
Homan, Fanny Emily Daughter F 17 Laundrymaid b Mortlake, Surrey
Herbert, Helen Jane Granddaughter F 7 Scholar b Mortlake
Could be a clue there?

EDIT:
Birth of Helen/Ellen from the GRO Index Search
HERBERT, ELLEN JANE (Mother's Maiden Name:) HOMAN
GRO Reference: 1873 D Quarter in RICHMOND SUNEY Volume 02A Page 330