Is she used to being crated? What's the reason that you need help with anxiety this weekend? I've got a lot of experience working with this in my own (now 5 y.o.) lab/hound mix ... unfortunately, no real good solutions.
Most of the drugs that are prescribed for anxiety -- basically, prozac, valium, and acepromazine -- are in the former things that take a while to work, or in the latter are things that are just plain not good for the dog. Valium straddles the two for me. I would never give a dog ace for anxiety or thunderstorms. It only immobilizes the dog; the dog is still anxious as hell, it just can't do anything about it, which isn't the best feeling for a dog to have.
Benadryl ... will make the dog sleepy for about 3-4 hours, but that's about it. The dog, if anxious, will just bull it's way through any sedative effects that benadryl will provide.
The most solid recommendation I can give you is to crate train your dog. That's also not quite possible in a weekend's time, but it might help contain the damage. Use a wire metal crate and not a plastic one.
If it's because you're leaving for the weekend and your neighbors are complaining, board her at a kennel for the weekend.
Edited to add: I have not had any luck whatsoever with herbal remedies, and I'm incredibly suspicious about anything like a 'magnetic' remedy.
[This message has been edited by superspeck (edited 5/4/2012 5:10p).]