I was really impressed with how much area the family had searched and they did check the places she knows.Is there somewhere she liked to go when she was younger? Have those types of areas been checked?
I ask because a similar missing scenario happened with a friend's dad. He was missing a couple of days in VA in the winter. He was eventually found (safe!) by railroad tracks. He used to love trains when he was younger. They theorize he may have headed toward the sounds of trains. He was about 15 miles from home.