Yes, but if you have Valium why would you take Benadryl? Valium has a shorter half life so you wont be as groggy.
Until you hit that 12 week mark you are going to be anxious, try maybe taking a warm bath with some lavender scented bath gel before you go to bed to relax your body and maybe it will help you sleep better. When you wake up from one of those dreams, just take a few deep breaths.
Valium is a benzo, and they can stay in your system for 40 days..but it depends on how much you took.
Homeopathic remedies basically don’t have any interactions with drugs, so as long as your doctor prescribed the Valium to you and you’ve used it before (just to make sure you know how your body responds), you should have no problem at all.
Ambien will make you go to sleep, a lot of times Xanax is perscribed for flights only because with Valium the residual drowsiness is extreme, the best for a short flight would probably be Ativan, as you will be alert easier but still will have the same effect (BTW all the drugs described besides Ambien, belong the the Benzodiazapine family of drugs)
It is very unlikely to be prescribed an excess of Valiu in the case of alcohol detox. Rehab generally will only give the very minimum of medication, if any at all and for the shortest time. It can take days for Valium and related meds to clear the system, especially if unapproved doses have been taken.