Advice for handicapped Mother of the Groom?

I'd advise asking your fiances mother. She'll know her needs best

You may want to consider plated v. Buffet and if it's buffet, having a plate made and brought to her.

Your venues and officiant should be able to assist with this. Please let them know early on so all accommodations can be considered early in the game. I also recommend plated dinner and a seating plan that will allow her easy access to her table at the reception (with a good vantage point of everything... entrance, dancing, cake, etc).

Make sure she doesn't have to spend a lot of time looking up at guests who are standing.

Make sure whatever vehicle she will be in can accommodate her wheelchair.

If you're doing a unity celebration that includes the moms, make sure she can do it (not up steps to light a candle that is higher than she can reach, etc.).

Will she be getting hair & make-up done with you? Can the hairdresser/MUA work on her with her in or wheelchair or will she need to transfer?

Make SURE that she gets a handicapped room at the hotel. Sometimes they promise a handicap room, but when you arrive none are available (had that problem traveling with my DH).

Everything that has already been said, and also - ask her. Sometimes we can't possibly think of everything. That way there won't be any surprises that day, and she will be comfortable and all accommodations will be made.

Make sure her seat at the table is easy to get to and that there is a table setting without a chair. Try to have her near the door so that she doesn't have to maneuver through all the tables.