Rebecca, I'm sorry that your question wasn't answered in a timely manner and I'm sorry to hear of this with your dog. I understand your frustration. When a benzodiazepine such as alprazolam isn't as helpful as we would like, we're left with a true tranquilizer such as acepromazine which acts as an anxiolytic (an antianxiety drug) by tranquilization rather than being a true anxiolytic. Acepromazine can be prescribed by your vet and dosing will need to be titred so as to provide the appropriate effect yet not sedate to the point that excessive somnolence (sleepiness) arises. Dosing is variable at 0.25 - 1 mg/lb every 6-12 hours but many of us think that dosages at the higher end of this range are too high.
You appear to be describing sundowners syndrome - a form of cognitive dysfunction in dogs and humans. It's conjectured that the dark and quiet of night magnifies the sensory loss in these patients which results in their anxiety and subsequent vocalizing, aimless wandering, and other misbehaviors. Other indications of cognitive dysfunction include disorientation, changes in social and interactive behavior - becoming "needier" or, conversely, more aloof - changes in locomotor and sleep cycle behaviors, and loss of housetraining.
Unfortunately, this is a progressive disorder and often vexes caretakers unable to control inappropriate behavior. If additional medical problems exist - brain tumor, e.g. - seizures may arise and prompt the need for anticonvulsant drugs.
Ancillary care involves physically and mentally stimulating exercises such as swimming, massage, and range of motion exercises, encouraging relaxation, ensuring that she is taken out frequently to minimize the cost of elimination "mistakes", encouraging reestablishment of daily cycles by feeding at regular hours and at least a few hours before bedtime, and administering the alprazolam before bed. Specialized diets rich in antioxidants may be of value such as Hill's Prescription Diet b/d. The monoamine oxidase inhibitor selegiline (Anipryl) is the only drug licensed for use for the treatment of canine cognitive dysfunction in the States. Many of us aren't impressed with the studies supporting its use, however.
Cognitive dysfunction in dogs is just as difficult to manage as is Altzheimer's in humans. I wish I had some magic for your dog. Please respond with further questions or concerns if you wish.