What you are doing is wonderful and it will be remembered by your mom for along time. I did this for my hubby when he turned 50. I don't know if you are in Indy or not, but I catered it with Johnathon Bryds. It was pretty cheap, and they bring in the food, set it up, have someone serve it for you and everything, I didn't have to worry about a thing. It was great, if you can't afford that, then do pasta or something you can make, and keep warm in crockpots. I'd call around and check prices, with the economy, it might be cheaper now to have it catered.
You could make her the queen for the day girl. That doesn't make any reference to age at all.
I would definately recommend that you buy disposable cameras and put them on all the tables. I did this and the pics we developed afterwards were a hoot!!!! People used the camera's and had alot of fun.
I would suggest music from Moms time and maybe let them dance a bit if there is enough room.
Get speakers to come up and talk about your mom, how they met, fun stories. Reliving the past is good when it involves good times.
I agree with the pictures. I made my husband a scrapbook of the party after we had all the pics done, and he still looks through it off and on and smiles. So anything you can put together before the party and then leave pages for after the party would be a special memento for her.
How about cards? Does your mom and friends play cards? Board games? Set up and area if you can and let them play. Try to make it games that don't take alot of time, but are still fun. Talk to your Mom about what her and her friends do now, that might help you with what to do.
Make sure you get a big enough cake, I didn't.....I was not happy about that, but everyone else didn't seem to mind......I had family flying in from all over the states, so it was nice to spend the time together and seeing my husbands face when he saw his brothers from out of state. He thought he saw wrong, the picture from that is the best. Video taping it is also a very good idea if you have a couple of people willing to do that for you, that would be great.
I'm sure it will all go just fine and be a great day to remember for everyone. Being together with friends and family is the best.