Question

Why does Ponyboy say he had the knife and he killed Bob when it was Johnny?*

O Pony isn't confused. He killed Bob.
O
Ponyboy is confused, potentially due to mental illness such as PTSD (post-traumatic
stress disorder)
Ponyboy is angry and wants to take the fall so Johnny doesn't go to prison
O
Ponyboy never says he had the knife

Answer 1

Ponyboy is confused, potentially due to mental illness such as PTSD (post-traumatic stress disorder)

Step-by-step explanation:

He wants to believe that Johnny isn´t dead.