He watched her with growing interest as she galloped toward him, for he saw that she was young and a stranger.

Probably she was from "the Springs," as she was riding one of Gates's horses and was riding him hard.
The rider drew in her horse and stopped as she came up to the children.
Keith heard her ask what was the matter with the little one, and the older child's reply that she was crying because she had lost her money.
"She was goin' to buy candy with it at the store, but dropped it." The girl sprang from her horse.
"Oh, you poor little thing! Come here, you dear little kitten.

I'll give you some money.

Won't you hold my horse?
He won't hurt you." This to the elder child.
She threw herself on her knees in the road, as regardless of the dust as were the children, and drawing the sobbing child close to her, took her handkerchief from her pocket and gently wiped its little, dirty, smeared face, and began comforting it in soothing tones.

Keith had come up and stood watching her with quickening breath.