Question

Why did Helen feel happy at Perkins Institution for the Blind

Answer 1

 Helen and Miss. Sullivan had scarcely arrived at the Perkins institution, when Helen started making new friends there. She was absolutely delighted to find that the children here, could very well understand her manual alphabet. 
It was inexpressibly joyful for her, to communicate in her own language. Until then, she was forced to converse through an interpreter, but now it was different.
Her new friends here were so eager, hearty and joyous.
For a child like Helen, these were wonderful reason to get Happy.

Answer 2

Helen and Miss. Sullivan had scarcely arrived at the Perkins institution, when Helen started making new friends there. She was absolutely delighted to find that the children here, could very well understand her manual alphabet. 

It was inexpressibly joyful for her, to communicate in her own language. Until then, she was forced to converse through an interpreter, but now it was different.

Her new friends here were so eager, hearty and joyous.

For a child like Helen, these were wonderful reason to get Happy.