Final answer:
Macbeth gains two major advantages from Malcolm and Donalbain's flight from Scotland: an unchallenged ascension to the throne and no immediate opposition to his rule from Duncan's heirs.
Step-by-step explanation:
The sudden departure of Malcolm and Donalbain from Scotland after the murder of their father King Duncan presents two significant advantages to Macbeth in his quest for power.
First, their absence allows Macbeth to easily ascend to the throne, as suspicions naturally fall on the princes because they fled, making them seem guilty of parricide.
Second, with Duncan's legitimate heirs out of the country, there is no immediate challenge to Macbeth’s claim to kingship, allowing him to consolidate his power without facing direct opposition from within the royal family.