By 1901 Mary (as STAGG) is enumerated as widowed and a niece in an ELLIS family in Croydon. Also in the household are two STAGG children, Hannah (18 b Kentish Town) and Ellen (10 b Cattle Market, Islington).
1901 ref: RG13/644/77/43.
I wonder whether Hannah might be the same child enumerated in 1891 as Maud BLIGH (7 b St Pancras)? Having now seen her baptism as "Maud Hannah" posted by Carole, I would think that looks likely.