Why was Mattie unable to find the sheriff or the undertaker in True Grit?
We saw in Chapter 1 how Mattie's father was murdered.
As Chapter 2 opens, Mattie and Yarnell (her guardian) are travelling into Fort Smith to take care of the body of Mattie's father. They need to find the city officials who can help them.
But they're nowhere to be found. Why? To find the answer, let's look a little further in Chapter 2:
"There was a jailer at the sheriff's office and he said we would have to talk to the city police or the high sheriff about the particulars of Papa's death. The sheriff had gone to the hanging. The undertaker was not open. He had left a notice on his door saying he would be back after the hanging."
So, we see that Mattie can't find the sheriff because he's at the hanging. As for the undertaker, his place of business is not open right then, so he's not there. And the undertaker too is also probably at the hanging, seeing as he put up a sign saying he'd be back after that. Practically the whole town is at the hanging!
Can you tell where Mattie and Yarnell are going next? Yes, to the hanging. We see how Mattie is such a tough and intelligent girl--she doesn't exactly want to watch the hanging, but she makes up her mind to not tell her mama about it, so that her mama won't worry about young Mattie seeing such a grisly sight.