I don't know if you have access to sous vide, but if you do, the 2 dishes you suggested could all be cooked in advance and then grilled to finish! I think it is a day you want to reduce as much cooking as possible and have the time for the day. Good luck and give your Mom a hug for me!
I have never done sous vide. This might be a good excuse to give it try. I can probably find someone with the equipment or break down and buy it myself. My only reluctance is that I have heard it changes the texture of the meat.
You are right, I will want to do as much ahead of time as possible, not only to enjoy the day, but because of where we are having the party. It will be at a community building (another term I dislike and have a hard time using is wedding or banquet venue. For crying out loud, it is a building, room or hall!). There is a very nice kitchen, but they don't want a lot of prep work done there.
My thought was to do the beef rolls ahead of time on the smoker and refrigerate overnight. The day of the party I will slice them and reheat them on a wire rack in a covered hotel pan with beef stock on the bottom to create steam. I have done this for similar things and it has worked well. I would do the same thing for the chicken thighs, with chicken stock.
urnmor - I think we are probably looking at around 50 people. Salmon is definitely a consideration. MikeMcQ's twice smoked salmon salad has become a staple. For some reason I have kind of lost my taste for pulled pork, I am not sure why. However, it just hit me that I could do a stuffed pork loin to compliment the beef. It is a work in progress, so we'll see where the journey goes!