In Flowers for Algernon, what is Charlie's relationship with his family after his operation versus how it was in the past?
Before the operation, Charlie was more a victim to his family than in any sort of "relationship." He was more of someone who had to be dealt with versus someone who could hold conversations and show love, etc... Rose, his mother, was in denial for most of Charlie's "early years" as to Charlie having any sort of problem at all. She constantly scolded him for not living up to unrealistic expectations and then was scared of him and his disability. Norma was just a child when Charlie was around her. She resented his presence because she would be the "responsible one" at home and at school. Matt meant well, but couldn't handle Charlie's disability nor his wife's attitude towards him.
After the surgery, when Charlie revisited the characters, Norma showed the most change. She had grown up and probably realized how childish and immature she was. After all, she was a child too when all of Charlie's problems were at the forefront. She was kind and I believe, if Charlie's surgery would have had a more lasting effect, the two would have develped a successful relationship.
As for Rose, by the time Charlie revisited her, she was going senile and was living in the past, assuming that nothing had changed with Charlie -- including his age. There was essentially no change in their relationship excepting the fact that Charlie realized how cruel and ignorant she was.
When Charlie visited Matt at the barbershop, he realized that Matt never meant anything wrong by any of his actions towards Charlie. Matt was simply stuck in the middle, trying to survive. Since Matt didn't even recognize Charlie, Charlie made the decision to not even tell Matt who he was. I believe he was trying to save Matt any guilty feelings for how things were when he was a child.