I would guess pre 1900. couple look elderly so would be in their 70 80s If you know where the family came from, you could look for a Madge in that area, on 1881 1891 census, and see what you get.
I am currently doing the same with wedding photos which span the early 20th century into the 1930s, some lovely outfits, we know possible family members on some of the pictures, but having to work out status given the way the pictures were a little more formally arranged.
Good luck.