Hey,
With 300 marks, you may get a rank between 246358-262168. You can check it here https://medicine.careers360.com/articles/neet-result-marks-vs-rank
Since you did not mention your category, I am assuming you are of general category.
You can definitely get a management quota medical and dental seat through All India Counselling for Deemed Universities. You can get the following colleges -
To get a complete list of colleges in which you might have a chance of getting MBBS/BDS seat, you can use NEET College Predictor https://medicine.careers360.com/neet-college-predictor?icn=QnA&ici=qna_answer
Regular exam updates, QnA, Predictors, College Applications & E-books now on your Mobile