Some of the responses seem harsh at first glance, but the message underneath is the reality of the situation.
I've been in a similar situation to your daughter (only I didn't report, so I can't even imagine the emotional turmoil that a trial would bring). It's amazing how many people you're surrounded by act like they're supporting you, but in a way, they make it all about them and their feelings. I'm not saying you're doing this, but it's incredibly frustrating when you feel like you have to be the strong one for everyone else, even though it's you that had it happen to them, it's you that lives with the nightmares, depression and anxiety that it brings, and it's you that had to stand up and talk about it.
I think you need to have an honest chat with your daughter where you haven't told her what you want to happen, and ask her what she wants to do, and say you'll support her. If she wants a big family Christmas, I do think going for an hour or two in support of your daughter is important. If she wants a quiet one, then you can make plans to make it cosy on a smaller scale.
Honestly, the cloud of grief that that incident brought me didn't lift for years. Little days of sheer happiness made such a difference. It almost allowed me to forget it happened, which was bliss. If your daughter wants a bit of escapism, I'd definitely try to support her in that. I think the worst thing you could do is completely go against what she wants so she either doesn't do what she wants to do, or she feels guilt ridden the entire day. It really is only one day, for a matter of hours.