Here is the location. There is additional information and helpful hints to read. I wish you the best in your difficult situation, I understand your concern and frustration. Wandering is often caused by getting lost, or being distracted by something. New environments often increase wandering because of their unfamiliarity.
Some people wander during the day, others at night.
Some wander for no discernible reason. Some people with Alzheimer's wander because they feel physically restless. It may help to take them on long, tiring walks. Then lead them back home, reassuring them about their safety and comfort there. Keep your doors locked, and install childproofing gates where necessary on porches and decks.