Hi CB,
I had wonderful luck in a pair of older neighbors. We lived next door for just a year, but they opened their hearts and we became close friends. They were more aunt and uncle to her...not quite as close as family, but affection and trust were obvious. We see each other at least yearly and when they are near her town, they've stopped to see her. The other resources were parents of her friends. Although she was isolated in elementary school and middle school, by high school she'd made friends with a great group of kids, and one set of parents became my friends too. So we would go rent a beach house together, etc. The other resource was church and its youth group, which was her main social life in middle school and high school...she loved going to the conferences, and as it was a diverse, liberal organization, she finally felt at home. I was startled by how much she loved the youth group, but she said they "got" her. It was such a non-pecking-order, non-materialistic kind of group, that she loved it.
I don't know if there's a UU church near you or if you'd be curious, but you could check it out, or any diverse, open-minded congregation. I think of Unity, Society of Friends, too. All of those have reputations for loving inclusiveness and a positive humanistic approach to faith. Their kids' programs, and the way the whole community often gathers intergenerationally, can be a huge support to a single parent.
love
Hops