The gentleman is holding a cane. GAR had annual encampments; there are online photos of canes from some of the encampments.
A thought, but possibly far-fetched…the man attended an encampment and upon his return home, for some reason the family dressed in period outfits? Another thought, a friend of ours used to be in civil war reinactments (his wife and children attended as well). They had very detailed period dress. According to the internet, that didn’t start until the 1960s. But, maybe GAR encampments allowed families to attend?

Added: GAR annual encampments were from 1866 to 1949.
Apologies for not adding sources; I don’t like to add unfamiliar links.
Added: the bar at the top of the ribbon may have writing such as official souvenir, representative, (a) year, delegate.