Sorry to hear about your grandfather's diagnosis - I hope everything works out for him attending the game.
Here's what I found at hangonsloopy.com:
osu.gameday
Persons with Accessibility Issues
Reserved season seating for persons in wheelchairs is located at the top of AA deck. Other accessible seating sections are located in the top rows of A and B decks in South Stands. Accommodations should be made in advance for seating in these areas. If accessible seating is needed day of game, then please visit Guest Services located near Gate 7. Other questions concerning accessiblity seating can be directed to the Athletic Ticket Office at (614) 292-2624.
Elevators are located near sections 7, 10 and 37. These elevators may be used for individuals needing assistance to their assigned seats in B deck or C deck.
Disability parking lots are located on the north side of St John Arena and Jesse Owens North (east of St. John Arena). Patrons with state issued disability placards will be allowed to park in these lots and are required to pay the $10 day of game parking fee. Shuttles will run from these parking lots to the east side of Ohio Stadium. Questions concerning disability parking should be directed to Transportation and Parking Services, (614) 292-9341.
Parking - Disability
Disability Parking will be located in the paved parking lots North of St. John Arena. This area will be accessible from the East and all vehicles will enter from Tuttle Park Place. A current state issued disability placard is required to gain admittance into this parking area. A shuttle will transport fans from the North St. John Arena Lot to Gate 18 located on the east side of Ohio Stadium. This shuttle will operate from 3 hours prior to kickoff until one hour after the game. Any RV/Camper with a disability placard or permit will be sent to WEST CAMPUS to park on Carmack Road. Shuttle service will be available from west Campus to the Sisson footbridge.