Made plans to chill at my place 3 days ago

Asked her today if she can drive here

Replies 5 hours later (after I comment on a snapchat story) saying she forgot she has family event and says she's knows I'll kill her

I think but not sure it's a BS excuse since she usually doesn't forget family plans

What to do?

Double down and tell her cancel it?

No reply?

Or say it's cool?

IMO I'm kinda indifferent but feel like I should be annoyed. She had 3 days to tell me and another 5 hours to reply.