Why did Nancy Clutter's friend, Nancy Ewalt, come over to River Valley Farm the morning after the murders?

Nancy Ewalt went to the River Valley Farm to accompany the Clutter family to church.

She was a classmate of Nancy Clutter's, and her name was also Nancy - Nancy Ewalt. She was the only child of the man who was driving the car, Mr. Clarence Ewalt, a middle-aged sugar-beet farmer. Mr. Ewalt was not himself a churchgoer, nor was his wife, but every Sunday he dropped his daughter at River Valley Farm in order that she might accompany the Clutter family to Methodist services in Garden City.