Sonia, to be eligible for NEET, you should have completed your 12th with Physics, Chemistry and Biology as your core subjects. You may have Biology as an additional subject but that is along with your regular subjects. For example, taking your case, you should have studied Biology atleast as an additional subject along with Physics, Chemistry and Mathematics. Studying Biology as an additional subject from NIOS will not qualify you for NEET. The alternate way is to study Physics, Chemistry and Biology again from NIOS.