I think the photo was taken at the public practice match at Maine Road on 17th August 1957 between the first team (Blues) and reserves (Maroons).
City should have played Sheffield Wednesday in the opening game of the season on the following Saturday (24th August), but that game was postponed as many of the Wednesday players were ill with Asian Flu, which was about to sweep through the country. As a result, City arranged another public practice match, during which Jack Dyson,(1st left sitting on the photo) broke his leg and didn’t play again for two years.
As to the black armbands, I’ve no idea, unless one of the directors say, or a prominent former player had passed on.