Hello

Based on the previous year cutoff the student need to score 550-650 to get MBBS seat in Tamil Nadu

So your score wont be sufficient at all.

You can check the cutoffs of previous year using the link below

https://medicine.careers360.com/articles/neet-cutoff-tamil-nadu

There will be sloght variations in the cutoff based on factors like difficulty level of exam, no of applicants, no of seats available etc

But such drastic decrease cannot be expected.

So try hard next time.

All the best!