The entrance exam will test you on your comprehension, broad understanding of social sciences and themes related to the political, economic and social history and aspects on religion and culture pertaining to Indian and World history for the ancient, medieval, modern and contemporary periods. JNU has recently changed its entrance examination mode but hasn't prescribed any books. So you may have to cover your Bachelor degree books for History. Arihant experts have Chapterwise Previous years solved papers but it might not help due to changed exam patten. RPH Editorial board has published JNU MA History entrance exam preparation book. That might help you.