Hello,
If I consider the previous year data .Then you have negligible  chances of getting admission in any of the government colleges in bihar even through state quota .Previous year last cutoff rank admitted for an abc candidate was 15016 for government medical college bettiah.
You might get some colleges in other states through all india quota.
The cutoff changes almost every year,so nothing can be predicted much.cutoff depends on the difficulty level of the paper and the number of students who appeared for the entrance exam.
Just hope for the best
Browse the link given below for detailed information.http://www.google.com/amp/s/medicine.careers360.com/articles/neet-cutoff-bihar/amp