What does winston write about in his diary?

He used to write memories, important moments in his daily life, political thoughts and criticisms.

Explanation:

Winston was in the habit of keeping a diary, in which he wrote whenever he felt there was a need to record something. In 1984, this habit became more recurrent and Winston began to write, in addition to memories of important moments of his daily life, thoughts, moods and, especially political criticisms and opinions, especially those related to certain political parties that did not fit the ideology that he defended.

b is the answer