what are best subjects for bsc(bio) 1st year ?

Hello aspirant,
Since, you mentioned that you will prepare for neet this year too by self study but bsc is your backup plan.
I suggest you to take regular bsc.
This involves chemistry, botany , zoology.
First year syllabus is very same wity neet preparation.
So, if you are preparing for neet you will be prepared for 1st year bsc exam.
This will also help you to UPSC also since, all these three subjects are mentioned as subjects in UPSC as well.
However, if you choose any particular stream with bsc like biotechnology then it will be difficult for you to prepare for neet.

All the best.