The birth cert for one of the children should gives mothers maiden name. Obviously of the Jewish faith, when you look at their neighbors.
Looking at the names of the children with them.........I'm guessing it's Symons or Simons.
Look through the 1881 &1891 census.
JACOBS, ELIZABETH. mmn.
MORRIS
GRO Reference: 1858 D Quarter in EAST LONDON Volume 01C Page 14
JACOBS, JACOBS. mmn.
JACOBS
GRO Reference: 1857 J Quarter in EAST LONDON Volume 01C Page 19
JACOBS, SIMON. mmn.
NATHAN
GRO Reference: 1858 S Quarter in EAST LONDON Volume 01C Page 9
JACOBS, SIMON. mmn.
SYMONS
GRO Reference: 1860 J Quarter in EAST LONDON Volume 01C Page 3
JACOBS, MARKS. mmn.
SIMONS
GRO Reference: 1861 D Quarter in EAST LONDON Volume 01C Page 13
JACOBS, MOSS. mmn.
SIMONS
GRO Reference: 1874 D Quarter in SAINT GEORGE IN THE EAST Volume 01C Page 420
JACOBS, HARRY. (Henry). mmn.
SIMONS
GRO Reference: 1876 S Quarter in SAINT GEORGE IN THE EAST Volume 01C Page 407
Steve.