My comment applies to folks who use pens, pencils, watercolors, oils, acrylics, etc. who duplicate photos, without abandon, and then peddle their products as art. I think it's great that your grandma loves your photographs. And it sounds like you've got a really cool show planned.
It's easy to spot a painting that's copied from a photo. Especially when the painting shows lens traits--compressed space, wide angle distortion, scenes that are not framed the way the eye actually sees, etc. I do not have a problem with artists who use photos to enable them to interpret scenes, subjects, or ideas. But to my thinking, a painting that is a blatant copy of a photo is worthless. I see a lot of these worthless paintings selling for a premium while highly original fine art photos are dismissed.
A joke: An "art lover" walks into a bar. He points to a nicely framed picture hanging on the wall and says to the bartender, "That's a curious photograph." The bartender replies, "Oh, it's actually a painting. ... I picked it up at an art fare. The artist is really talented. His paintings look just like photographs."
I've thought about going to art fares to take pictures of all of the drawings and paintings that are direct ripoffs of photographs (Celebs, historical landmarks, etc.). After taking the pictures, I'd print them up, frame 'em, and try to sell 'em. Odds are, not a single one would be purchased for a mere fraction of the same price as the first gen ripoff.