I'm guessing it's from the 60's. The bride has the Marlo Thomas sort of hair style and the tux's are not recognizable to me, I worked in a tux shop in the mid 70's. I don't recognize the background at all.

A 74 bride as well?

Cut of the tuxes look similar to the ones the guys had at our wedding. Also the shirts ... though is that a print on the suit jackets? OMG! And bow ties were all the rage.

Another possibility ... where did your Mother work at the time? perhaps contact them and see if they can identify, or can refer you to one of the former employees who might.

Hope you find out