Why did Ann not answer when the man yells “anybody here?”

In context, Anne was afraid. She didn't know the man, and she didn't want to put herself in danger.

"Anybody here?

It echoed again. When it stopped, it was strange how much quieter it seemed than before. You get so used to silence you don't notice it. But the sound of his voice was nice, a strong sound. For a minute I almost changed my mind. It came on me in a rush, very strong. I wanted to run down the hill through the woods and call, "I'm here." I wanted to cry, and touch his face. But I caught myself in time, and stayed quiet. He turned, and I looked through my binoculars watching him. He was walking back to the wagon, with his mask hanging down his back like a hood.