My in laws will be celebrating their 50th wedding anniversary this weekend. What can I do for them that will make it a bit special?

Just some background so you know where they are at: He has quite severe senile dementia and has been living at a care- hospital. She is alone now, in their home/apartment. She is throwing a party this weekend and there is going to be a good amount of people showing up. I am not just going for the party, but also to assist with work and arrangments, as she is wheelchair bound with MS. Any suggestions as to how to help make this a wonderful and pleasant experience for everyone? (including 4 grandchildren ranging in age from 12 to 7)