Final answer:
Macbeth plans to 'make assurance double sure' in regard to Macduff by arranging his murder, as he views him as a threat to his throne, driven by the witches' prophecy.
Step-by-step explanation:
In Shakespeare’s Macbeth, the title character plans to “make assurance double sure” regarding Macduff by having him killed.
Macbeth fears that Macduff poses a threat to his throne, and this fear is exacerbated by the witches' prophecy about Macduff.
To eliminate any possibility of Macduff challenging or overthrowing him, Macbeth decides that he must go beyond mere caution and take decisive action, which involves orchestrating Macduff's murder.
This determination to cement his security as king results in a series of violent acts that ultimately contribute to Macbeth's downfall.