Ponyboy resents the fact that Cherry has a comfortable, easy, secure life while his brother, Darry, works two jobs to make ends meet. He is also upset because he believes that Cherry is only helping them out because she pities them. But, in the end when they say goodbye, Ponyboy asks Cherry Valance, "Hey, can you see the sunset from the West side?"
I guess she wanted to get to the Lancelot's room sneaky using the key she has got. And she put on the socks as she wanted to look not so ladylike. But it's still not clear for me.
