Hi
Do you have their marriage cert?  (Mar Qtr 1881, Prestwich Vol 8d Page 445, for reference).  It would help to know Mary's father's name/occupation.
Interestingly, in the 1881 Census, Mary's pob is given as Holt, Hereford.  (RG11; Piece 3955; Folio 125; Page 9).
There is a Mary Bentley, bc 1854, servant, born Herefordshire, in the 1871 Census; unfortunately not with family:
RG10; Piece 3019; Folio 50; Page 7
in the Deeley household, Cradley, Worcestershire.
Kind regards
Gaie