Well, good on you and granny. I've got kind of a similar story (no pictures, dane it.)
I had gotten out of shooting for many years, it wasn't a big priority for me for a lot of years. I kind of thought I had fired enough rounds in Uncle Sam's Fun Field Trip To Southeast Asia I was lucky enough to be a part of. After the Clinton Gun Ban expired, I started shooting again occasionally, it became more fun and I shot a lot more. But my wife didn't like guns too much, and refused to go shooting, she didn't even want to see guns, let alone hold one.
Fast forward to New Years Day 2009. There had been a murder of a young mother a few blocks from our house over the holiday. My wife spends a good bit of time home alone, as I drive a truck for a living. I'd heard a little about this murder before I left, but no details, just that a young woman had been found murdered in her home.
I got out on the road and my wife called and asked if I'd heard about this crime, and I told her I'd heard early reports, but nothing more. She filled me in on details, and told me she was a little scared. I reminded her that my pistol was up in the small safe beside the bed, she knew the combination. It had one loaded in the chamber. She was worried she didn't know how to use it right, so I told her to get my old Ruger Service Six out, she had seen it and knew how to load it, even if she didn't want it near her. She got it out and loaded it, and said she felt better.
Got back home and told her it was time for a range trip if she expected to have a gun handy to defend herself. I took her over, and with the help of one of the range instructors (more from him than me) she got started shooting at age 70. She'd never shot in her life, but within the first cylinder she got on target with them out to about 25 feet. After going through a 50 round box of ammo, she was shooting the center out of the target at that same range. I can't remember seeing her any happier than when she was blazing away at that piece of paper.
She's been shooting better than a year now, she continues to improve, and is shooting at longer ranges than 25 feet, she's not bad doing the 10 meter course at our range these days. Age is no obstacle to learning to shoot.
You're a good grandson, tell granny I'm proud of her taking responsibility for her safety, and to keep shooting!