Help please, I am looking for any information that help, I am also new to this South African geneaology.

In my tree I have a family of four,
WILLIAM HENRY HANCOCK b.1856 England
MARY ANN HANCOCKb.1856 England
EDITH E HANCOCK 1881 CAPE COLONY
ROSE MARY HANCOCK 1883 WOODSTOCK CAPE TOWN.
In 1890`s they are living in WOODSTOCK CAPE TOWN
In the 1901 census they are living in England in Birmingham.
IN the 1911 census they have dissappeared again, I am assuming that they have returned to South Africa, But i am unable to locate them.

Can anyone help me??