Final answer:
The excerpt provided does not include the required lines from the short story 'Lamb for the Slaughter' to determine the best line supporting the statement.
Step-by-step explanation:
The question asks for a line from the short story 'Lamb for the Slaughter' that supports the statement that Mary Maloney is a content and loving housewife while Mr. Maloney is the complete opposite. Unfortunately, the provided excerpts do not include lines 21-83 of the story. Without those specific lines, it is difficult to provide a definitive answer. However, there may be other lines or scenes in the story that demonstrate Mary's content and loving nature, such as her reaction to her husband's news or her actions later in the story.