I have found these residents enjoy garden walks. Also if your able to get an Ipad you can google things that interested them in the past eg nature, birds, trains, boats even film clips of their favourite singing group. If they were travellers you could google places they have been and talk to them about this. They may not be able to respond but you can normally get a lot from facial expressions. It is a great way to do reminising with them.
15 Activities for Loners and Introverts in Senior Care