I'm fairly certain that the crank with the 26 granny gear can be changed to a 22, I would highly recommend doing this. You will very much appreciate having the lower gearing.
My lowest bike gearing is a 22 front, 34 rear, and with 26 inch wheels it gives me a very nice low gear that I have used a lot and I am about 15 years younger than you.

The way to know is to get the BCD of your crankset, this will tell you the smallest chainring you can put on.

The only downside to going from the 26 to a 22 is that when you change from the 36 to the 22, you will have to study up a gear or two at back, but balanced against the lower getting, worth a click of two on your bar end shifters.