My gut tells me...
The owner lost money on 5 previous events. I'm guessing that he foresaw losing money on next weeks event. So, he got rid of her to keep 100% of revenue.
So you're saying she was in charge of actully lining up the acts, not just planning the events? There's a difference. In that case, she's more of a booking agent than an "event planner."
She's still probably owed dough for what she's already done, though.