Thank you for bringing your question to Just Answer!
It sounds as if your friend is "star-struck" and is not interested in hearing any opposing opinions. B's behavior sounds very bizarre, and perhaps spending ten days with him will be enough time for the glow to wear off. Maybe if she has to clean up after him the way you had to clean your car his behavior won't seem so charming.
Your friend clearly knows where you stand. And she doesn't sound like she's thinking very clearly right now (the 'red bull emergency'). The more you try to get her to see the red flags that are so obvious, the more she may feel she has to "defend" him. It may be more effective to adopt a "to each her own" attitude when with her.
It's virtually impossible to convince someone who thinks she in love that she's making a mistake. I know you're worried about her, but her shutting you out of her dinner party shows how determined she is to convince herself she wants to be with this man. Hopefully, if he continues to show odd behavior like he did on the trip, spending 10 days with him might be the antidote that wakes her up.
As her friend and relative, about all you can to is be ready to comfort her if /when she gets her heart broken. It's hard to stand by and watch a friend make a mistake, but trying to talk a 62 year old woman out of what she may see as her last chance for love, could drive a wedge into your relationship with her.