I can get admission in MBBS in private college with 300 marks
Hello Rumana.
As per the previous years' records, the cut-off for admission into many private colleges is close to 250-350 marks. So, you might be able to get admission into some medical college but not the best and top medical colleges. For more details about colleges and their cut-off check this: https://medicine.careers360.com/articles/neet-cut-off
And to get a list of colleges you have chance to get a seat in, check this: https://medicine.careers360.com/neet-rank-predictor
All the best.