My 2 cents worth here V. :)
I cooked at a Retirement Home for 18 months, after returning to New Zealand after many years in Italy. What a change of pace that turned out to be!
First of all, you need to remember that most, if not all of the residents, will not have their own teeth. Also bear in mind that many will have ill fitting teeth to boot. :( So beware of anything that requires much chewing. Someone has mentioned chicken wings but I absolutely do not agree with them being served. Apart from the chewing factor, they are messy. Eighty plus year olds were brought up in a much more genteel era and I dont believe they would appreciate handling greasy anything! Also, try to have mostly soft/ish foods, many elderly require their food to be nearly pureed.
As there are 140 residents, you could probably count on 10 to 20 diabetics so any sweet items made with a sugar substitute would be appreciated Im sure.
I am not quite sure if you are meaning the Brunch has been taken care of, and you are providing Finger Food from 2 pm, or you are intending this food to take the place of the evening meal. If you are thinking to provide food from 2pm, I suggest to keep it to 2 to 3 items to begin with. Many will still be feeling the effects of Brunch around then!
Have you considered having an afternoon tea?? Considering Brunch has been served, and assuming a light evening meal of Soups etc may be available later, this may be ideal.
* Ribbon Sandwiches with fillings you have mentioned, plus maybe smoked salmon, cucumber,cream cheese and lemon pepper ( a little!) I would make curried chicken sandwiches, great with a few sultanas added.
* Little Vol au Vents with a creamed mushroom or asparagus /egg mix. Smoked oysters in a light white sauce are wonderful too. I use tinned ones and incorporate the liquid.
* Baby Quiche. I use mini muffin tins and fill the pastry with for eg: Goats cheese and thyme...pesto, spinach, fetta....diced ham and pineapple.....smoked salmon offcuts with dill etc etc.
* Stuffed Button Mushrooms. Try blue cheese and walnut....bacon with a hint of chilli and heaps of parsley......your American style crab ones too! ( Have not tried them myself!)
* Mini Fritters. I make them with Paua ( abalone) mussels, oysters, corn and bacon, etc. Put a dab of sour cream and herbs on the seafood ones, avocado salsa on the corn type ones. Hands can get shaky, so toppings need to adhere to the food.
*English Scones with Jam and Cream!!! My favourites. I use a lemonade and cream scone recipe, if you would like it please PM me. Just split and put on some strawberry/raspberry preserves and a flourish of whipped cream.
* Madeira Cake...a lovely buttery cake that needs nothing other than a dusting of sugar
*OR, instead of Madeira, something old fashioned such as a ginger cake/bread
* Baby Meringues sandwiched with whipped cream and lemon curd or flavour some with rosewater and tint pink for the MIL! Decorate platters with fresh roses/petals.
* Little glazed fruit tartlets.
Just some ideas. The most important thing to remember is that, as has been mentioned, appetites will be small. Having a huge repast laid out may not achieve the desired effect whereas a smaller selection of exquisite little things may just do the trick.
Best of luck and do let us know how it goes. Eventually!! :)