Sounds like her grandfather needs a nice heavy mouse. She could disassemble a modern mouse and add lead weights to the inside until the weight and balance were right.
Touchpads are IMO less ergonomic and less intuitive than mice, sounds like her grandfather could use an extra bit of both.
A touchpad on a laptop is less ergonomic than a mouse on a properly arranged desktop. But a touchpad on a laptop is more ergonomic than a mouse on a laptop unless you set up your laptop like a desktop (place it on a stand on a big, clear desk with an external keyboard in front and a mouse pad to the side). Trying to use a mouse with a laptop that is sitting on your lap is, in my experience, invariably awkward.