Reason for scaring Mala by finding a box:
Mala found a box which belonged to her grandmother, and she got scared because she thought it was a treasure chest. The reason behind Mala getting scared was her grandmother, who had hidden her belongings in the box. Mala was not aware of this, so when she found the box, she thought it contained something mysterious or frightening.

Role of Nani:
Nani played a significant role in scaring Mala unintentionally. She had kept her things in the box without informing Mala about it. This lack of communication led to Mala's fear when she stumbled upon the box. Nani's actions were not meant to scare Mala, but her secretive behavior caused confusion and fear in Mala's mind.

Conclusion:
In conclusion, the reason for scaring Mala by finding a box was Nani's hidden belongings. The lack of communication between Nani and Mala resulted in a misunderstanding that led to fear. It is essential to communicate openly and honestly to avoid such situations and prevent unnecessary fear or confusion.