Why do you think Anagha’s mother wanted her to know the story of the Buddha?
Anagha was travelling to Varansi on a school trip. Sarnath, a place in varansi is the place where Buddha taught for the first time. After attaining enlightenment in Bodh Gaya he travelled to varansi where he started spreading his teachings. The story and message of Buddha are inspiring hence Anagha’s mother wanted her to know the story of Buddha.