Think about it
Bholi's real name is Sulekha. We are told this right at the beginning. But only in the last but one paragraph of the story is Bholi called Sulekha again. Why do you think she is called Sulekha at that point in the story?
The name 'Bholi' means 'simpleton' — it is a nickname that encapsulates how her family and society have always seen her: as a backward, helpless, voiceless girl of no consequence. Throughout the story she is called Bholi, reflecting how others define her by her limitations.
The name 'Sulekha', by contrast, is her real, given name — a proper, dignified name. By using it in the penultimate paragraph, the narrator signals that the transformation is now complete. Sulekha speaks in "a voice that was calm and steady", without a trace of stammer, and announces a confident life plan: she will serve her parents in their old age and teach at the same school where she learned so much.
The shift in name marks the moment Bholi fully reclaims her identity. She is no longer the simpleton the world dismissed. She has shed the label 'Bholi' through education, courage, and self-determination. Using 'Sulekha' at this precise moment is the author's way of saying that the real Sulekha — intelligent, articulate, and dignified — has finally emerged from behind the belittling nickname.
Answer: She is called Sulekha at that moment because her transformation is complete — by speaking calmly and asserting a life plan without any stammer, she has shed the 'simpleton' label and reclaimed her true, dignified identity.