1. Granny didn't have her gun loaded.
2. Granny should've gotten the youths and herself in the house immediately when she first saw the perp approaching, locked the door, called 911, and stayed in the house.
3. Granny let the perp grab the grandson's shovel.
4. Granny waited to shoot until the perp was almost on top of her. If the perp was just a little smarter, he could've easily rushed her, grabbed the gun and shot all three innocents.
5. Granny wimped out and just shot to wound. A more determined aggressor very likely could've continued the attack, seizing her firearm and shooting all three innocents.
I'll give Granny a grade of 'D'.