Did i use the correct "theirs" Do guys shop for their own clothes or does their mom do it for them?

The correct answer is C) He has not forgotten or rejected his family or his Navajo culture.

Based on this excerpt, what can be inferred about Nantai is "He has not forgotten or rejected his family or his Navajo culture."

We can base this answer in the following part of the excerpt: "...but everything else was the same. His eyes shone bright and clear, and his smile was as wide as the sky. Atsidi recognized him as if he’d seen him only yesterday..."

This excerpt indicates that although with some natural changes due to the passing of time, Nantai was the same. White customs and clothes were now part of his life, but the core Navajo beliefs and culture were well within him. Nantai never denied his origins. That is why Atsidi recognized him as when they were children.