Hi Jaylay

A bit hard without being able to see the whole photo (e.g. the background has been removed, and they may have been cut off at the legs

) but it looks like 1860s, just going by the clothes and hair, formality of the portrait etc. I'm not sure, though.
As for the clothes, you would have worn your absolute best clobber to a photo session, Sunday best, or even borrowed clothes if you didn't have anything flash yourself. I've read that some photographers kept a "dressup box" of bits and pieces that could be worn for a portrait!
Cheers
Prue