What does pony boy get upset about after Jonny gets back from getting supplies (can you guys please help!)

Dally was upset because Johnny went back into the burning church. Dally clubbed him because he had fire burning on his back and Dally didn't want Ponyboy to go back in the church.

Explanation:

It is very significant.  the title of the book refers to the fear and safety that the cover of night brings.  night is the time when the ss came for the prominent jews in the communities both before  the jews were evacuated to the concentration camps and also in the camps themselves.  in this regard, night was a time to be feared since you couldn't see what was coming.  in the book, the victims of the concentration