Hello dear student, I understand your concern as you ask for the best books for biology for neet 2020. So as the handful amount of time is left I would suggest you to refer books those you can study at this time . Firstly I would suggest you to to properly understand biology books which is NCERT book is considered to be your God in preparation as more than 90% questions directly come from NCERT that can be in indirect language. but I would suggest you to kindly refer objective question in books at this time like previous year questions from Aarihant's and also MCQ question banks from MTG etc . You can also refer objective biology by Dinesh. I hope this is helpful to you

Thank you

Biology Best Books:

NCERT Biology Class XI and Class XII textbooks
Biology Vol 1 and Vol 2 by Trueman
Objective Biology by Dinesh
Objective Botany by Ansari
Pradeep Guide on Biology
GR Bathla publications for Biology