Reluctantly, I vote B (since everyone is already aware and willing to be understanding about it). I also vote for a carefully worded invitation wherein you take the high ground while letting everyone know she's a pain in the ass and made you change things. You could even add in a bit about setting the date now for next year's party so you don't have "this kind of problem" again.

It's possible that I'm too accommodating though, as people have said (though usually they don't say that while it's to their advantage).