Question

Nitya has donated all her old books to the library change into passive voice

Answer 1

All Nita's old books had been donated to the library by nitya

Answer 2

All of Nitya’s old books have been donated to the library (by her).

‘her’ is a pronoun and isn’t necessarily added to the passive voice of a sentence as ‘Nitya’ has already been mentioned.

It isn’t wrong though, it’s correct either way.