Final answer:
The downfall of the Mughal Empire in 18th century India was chiefly due to the expanded influence and control of European colonial powers, particularly the British East India Company.
Step-by-step explanation:
The Mughal Empire in the 18th century India was not brought down by any invasions from the Mongol Empire, nor the cruelty of Sultan Akbar. The downfall was mainly due to an increased European presence, specifically the British East India Company, which capitalized on the empire's decline to expand its trading ventures. This increased presence of European colonialism eventually allowed the British to gain control of the entire Indian subcontinent, eclipsing the power of the Mughals.