Step 1: Recall from passage.
The passage clearly states that coconut belongs to the family Arecaceae.
Step 2: Eliminate incorrect options.
- Gramineae → Family of cereals like wheat, rice, maize.
- Leguminosae → Family of pulses.
- Anacardiaceae → Family of mango and cashew.
Step 3: Conclusion.
Thus, the family of coconut is Arecaceae.
Final Answer: \[ \boxed{\text{Family of Coconut = Arecaceae}} \]