Would you attend your boyfriend's grandpa's funeral if you didn't know him?

My boyfriend asked if I would go. I met him once a few days before he died and my boyfriend said they weren't really close. He didn't seem upset about his grandpa when I talked to him on the phone, though I'm sure he's a little sad because it was his grandpa. I just kind of feel uncomfortable going since I didn't know him and don't really know his family. The funeral is two hours away and I already have commitments that day. Do you think sending his immediate family a card will suffice or do something for him other than go to the funeral?