Thanks. I’m referring to PR renewal application as he mentioned it was returned to him for not filling one of the questions.There is no "work history" in the citizenship application. I think you are referring to Q11 (which asks for all activities during the eligibility period).
You can't leave Q11 blank. If you did, then the application will most likely be returned as incomplete. If your wife did not work, she should have provided the dates and mentioned she was unemployed.