Computing with your grandma
I have taught elderly people to use computers for several years. Their biggest desire is to email and biggest fear is that they may damage the computer. . Use a mouse to minimize movement required. Avoid all devices with touch screen and small printing. Assure her that she cannot hurt the machine and teach her the basics. After that leave her alone and answer the phone when she calls.
Get your grandma an old computer with a keyboard and mouse that are easy to use. (They seem to have less fear of hurting a keyboard)