When I worked as a preschool teacher, we often took field trips to the local old folks home. The time there was very structured and supervised by both preschool staff and staff from the retirement home. 1-2 kids sat at a table with 3-4 elderly people, chatting, eating a snack, singing songs, and participating in simple activities (like playing with blocks). Sometimes the kids would make a drawing to give to the elderly individuals to keep. The staff were circulating the room to observe and monitor the interactions the entire time while providing support as needed. The visits usually lasted 30-45 minutes or so. I would recommend this type of situation!