From somewhen early in the last century:
The two boys in the back are Hans and Ralph ('Doc'). I'm not really sure which is which, but I suspect that Hans is the rightmost most of the two. He always appeared to be the most 'sober' of the two, but the was the top joker amongst the boys.
My best guess for the young woman behind Martha is Grandma Evah, and that she would have been in her early 30s.
So, Martha, 104, Gladys 105, and Dad 98. Happy Birthday, Mom!!