PT mom....just a thought...directly outside the very nice cruise terminal, with large elevators to the ground level. Just outside lf there is a fully manned taxi stand. Many of the taxis I saw were capable of storing a scooter.
Québec city is beautiful and well worth seeing, even from a taxi. Its a special place.
Although we walked into town directly from the ship, returning to the ship we took a taxi, as my hip replacement didn't give me the milage I anticipated!
Good Luck and safe journey.