Hammer home means to emphasize a point strongly and repeatedly. The correct answer is this meaning because the expression is used figuratively, not only by its literal words.

Examples:

• The speaker tried to hammer home the importance of honesty.
• In an HSC essay, Hammer home can express this meaning: to emphasize a point strongly and repeatedly.
• When this expression appears in a passage, connect Hammer home with the idea of to emphasize a point strongly and repeatedly.