I'm sure it wasn't Ms.B or Patricia telling security to assault guests.
I don't know the contractual arrangement between them and the hotel either, however, whatever the terms, statutorally you are a 'guest' of the hotel because you are on it's property - but you are also a guest of the promoters because they are representing the event and have agreed to hold themselves out to the public as hosts. Unfortunate for them as it may be, though they didn't instruct security to assault guests they are the first line of authority on-site unless they are just being used by the hotel sales office as party bait. So, are the promoters responsible for security's lapse of control, no. But the promoters do have a responsibility to attempt to apply some control on the situation. They do have a responsibility to have some knowledge about the level of reliability and conduct of the hotel's staff. And I wouldn't be telling them something they don't already know. It's their brand that's being marketed by the hotel, if not themselves in addition. And I'm sure both ladies would be very concerned if they knew you had been assaulted by staff at their party. Security slugging someone is not an act of a cataclysmic storm, earthquake, or power blackout. It's the act of a business out of control. And it's another example of how Halloween can turn in to a party night more dumb than many others.