NEET

With 439 marks and a 3 Lacs rank in NEET, you can easily get admission in MBBS colleges with the SC category in Bihar. You have good chances of getting a government seat and obviously private ones also. Although the options for government may be limited due to high cutoff of government colleges as there is low availability of seats and high competition. As you belong to the SC category, this will help you to secure the seat more easily as compared to other categories.

442 is a very decent score, and you may face difficulties in getting a government seat despite belonging to the SC category. As you have not mentioned your state, we are talking in general terms only. Although you still have chances of getting a government college, as the cutoffs for the reserved category are lower than others. If you wish to get admission in a private college, you can easily get a reputed college with this score.

With a 658 score and 2821 EWS rank in NEET, you have more chances of getting into college based on your EWS rank rather than your All India Rank. The EWS category rank is significantly better, allowing you to access colleges with lower cut-offs within the EWS quota as your EWS rank (2821) is much better than your potential All India Rank based on your score, which would likely be much higher. You'll be able to secure seats in good institutes with your rank; you can use college predictors to get a list of expected colleges.

No, 184 marks in NEET are not enough to get a government college for BSc Nursing. Government seats usually have higher cutoffs due to low availability of seats and higher demand. Although you may get a private seat. Most private institutes conduct their own entrance exams for admissions in nursing. So if you want to get admission in a very good private college, you may be required to appear for their entrance exam, and for a government seat, you need to reappear in NEET. The cutoffs for government B.Sc colleges  are however not very high but still a better score is required.

Yes, you can deifintly get seat with 355 marks in NEET if you belong to OBC catagory. The chances of getting a government college are relatively low because of high cutoffs of government colleges but you'll get a private college easily. If you cannot secure a seat in a government college with this score, you might explore private medical colleges where the cutoff might be lower or if you target is only getting a governent seat, you need to reapper for the exam and score a good rank.

With 254 marks in NEET, you can get admission in BAMS or BHMS if you belong to the EWS category. You only have chances of getting admission in a private collge because government seats are highly competive due to low seats intake. For the EWS category, the NEET cut-off is generally considered to be around 162 marks (50th percentile), and as your score is more than this, you'll not face any problem in getting admission in BAMS or BHMS. You can use Shiksha's college predictor to get a list of expected colleges.

90 marks in NEET is a very low score to get even a private college and that too with the lowest fees structure. Your marks are much lower than the cutoffs of private institutes. However, depending on the state and specific college, there might be a slim chance in the final rounds of counseling or for a very low-ranked private institution. You are suggested to reappear for the exam and get a good score so that you can get admission in a good college.