"According to figures given by the Indian Ministry of External Affairs in 1980, among the 3.8 million people of Indian origin in Nepal, 62.8 percent had acquired Nepal’s citizenship -  Dr हर्क गुरुङ"

Thanks for your insight @Kishorlimbu. if nepal government is willing to give indian people nepali citizenship i am astounded on why the same nepali govt. is not willing to give nepali citizenship to bhutanese refugees in nepal. afterall they are the nepalese.