"All the Years of her Life" refers to the culminated pain Alfred's mother has experienced during the course of her life, leading her to be broken and frightened under her façade of strength. In this story, she is pained by Alfred's repeated delinquency, such as his problems with petty theft that lead to him being fired from his job in the pharmacy and almost arrested. However, the story gives several hints that she has been broken in other parts of her life.
For example, when they get home after Mrs. Higgins's calm and self-assurance has saved Alfred, she warns him not to tell his father, who works at night, anything about what happened. This suggest that the father might react with rage. Alfred also remembers that his mother
had sat alone in the kitchen the night his young sister had kept repeating doggedly that she was getting married.
It sounds as if his mother very much did not want the sister to get married. We don't know why: did she think it was a bad marriage decision, or did she regret losing a daughter who was a buffer against Mr. Higgins? Whatever the reason, Alfred realizes that other blows that have helped break his mother.
These hints of other issues suggest that Mrs. Higgins has had to put up a façade to hide her fear and grief for all of her life. Alfred, as he realizes, has not been her only problem.