If Agnes was aged 6 in 1901, then she won't appear on the 1891 census?

But maybe this is the family you want?
1901 census: Reference RG13, Piece 3227, Folio 127, Page 13
Chapel House, Denby, Derbyshire
Hancock, Isaac Head M 39 Coal Miner - Gitter b Stanley Common, Derbyshire
Hancock, Annie E Wife F 36 b Spondon, Derbyshire
Hancock, Agnes A Daughter F 15 Factory Woollen Sempstress b Smalley Common
Hancock, John G Son M 11 b Denby
Hancock, Flora E Daughter F 5 b Denby