What comes to Ponyboy's mind when he sees Bob's picture in the yearbook?no

Basically, when Pony sees Bob's picture in the yearbook, he just starts to wonder about Bob as a person.  He had never really thought of what Bob was like -- he had just seen him as a sterotypical Soc who was always a jerk (or worse) to the Greaser types.

But now he starts to wonder about Bob.  He wonders about the Bob that Cherry Valance knew.  He wondered about whether Bob had a brother.  He wondered how it was that Bob was (according to Randy) the best friend a person ever had.

He wonders a lot of things like that, but the overall idea is that now he is seeing Bob as a real person.

For more details, look this up in the book -- it's right at the start of Chapter 11.