@Nikki237 Sounds like a fairly non-risky booking to me. As Normen pointed out, I would be very clear about not having anyone else over, or they might think that it's fine to have their son and family come over for a few days and stay with them.
Their initial message shows a lack of understanding of how to communicate with a host- you don't just start with questions, you show a little common courtesy, like "Hi XX, we are searching for places to stay in Victoria and yours looks nice. Would there be space to park....".
But your response was perfect and ellicited a more informative message back. I've had the same experience with newbie guests, who turned out to be fine guests.
Newbie seniors might need a bit of explanation as to what renting an Aiirbnb means, as many seniors have only stayed in hotels or traditional B&Bs before and might have unreasonable expectations, like you providing breakfast, or getting clean towels every day. So just make sure they "get" it- that it is neither like a hotel, a B&B, nor a long term rental where you can just invite family and friends over.
That said, you can play things by ear. A friend who hosts in Canada has a repeat senior couple who book a few days every few months- they come to see their daughter and grandkids, but prefer to have their own quiet place to go back to. There is another senior couple in town they are friends with and like to have over sometimes for a couple hours for drinks and a game of cards. My friend, the host, has no issue with this and doesn't try to charge extra or anything.
If these guests follow through and book with you, I could see them also becoming repeat guests if all goes well.