Suggest some best books or sources to prepare for this exam.and any common topics for other exams?
I suggest you some books to prepare for NABARD bcoz In hard book materials lot of books are there for different subjects and topics
For maths: M.tyra, Rakesh Yadav
For reasoning: R.S. Aggarawal, B.S. Sijwali
For General science: Ram Singh Yadav