Where did you get the name from? have you checked the birth indexes to find her birth? Do you know anything about any nationality linked to her family? I don't find a Hoff at all, but wonder about an accent changing the sound of the name somehow?
What about this one?
Fanny Blanche Happe born December quarter 1886 Knaresborough Yorkshire 9a 101
In the 1901 census they are at
80 Westminster Bridge Road, Waterloo Road, Lambeth, London
William C Happe Head M 38 Restaurant Superintendant Germany (German Subj.)
Adelaide Wife M 39 Gloucestershire Bristol
Reinald W Son 16 Electrical Engineer Yorks Harrogate
Blanche F daur 14 Yorks Harrogate
Lilian C daur 8 Durhan S Shields
RG13; Piece: 403; Folio: 53; Page: 43
Most of the other similar names are showing as Hope, a bit too English sounding unlike Hoff.