Keep her home with a cell phone. Text or call every hour. Leave her plenty of cereal, juice and sandwiches. She will be fine.
a lot of states don't have laws against leaving children home alone, it's on the paŕent to determine if the child is responsible enough.
i suspect that's why it's not illegal, shyt happens and young kids can stay put and feed themselves if the house is safe and the parent can check in.