Well, one thing you can do is try to take charge, since the organizer (who didn't do much organizing, it seems) is dropping out. I would email everyone, including the drop-out, and say, "Since we've been planning this for six months and the time is getting close, we need to hammer out a few final details. I volunteer to host the event at my house [address, date, time]. Joe is now unable to make it, but he has all the bottles; Joe, since you'll be out of town during the party, can you arrange for someone to bring the bottles to me on [date before Joe leaves town]? For everyone else, please get back to me ASAP and confirm you'll be attending." Or whatever is relevant for your situation.