What disease causes paralysis in the feet first, spreading upwards quickly?

It sounds like nueropathy. There are several different varieties. My wife is going through her third bout of peripheral neuropathy. The symptoms you cited are similar. Guillan-Barre syndrome is a possible culprit. Also a form of nueropathy. The 'sheath' that covers the nerves wears away, that's what makes the extremities tingle and then slowly die leading to paralysis. It's a drag watching someone you love go through it. You mention grandpa was riding his bike hhome from the bar. There is a nother kind of neuropathy...'alcoholic nueropathy'. Do a web-search, you'll be just as interested as you are in the story of Grandpa's death.