A government BAMS doctor enjoys the status of regular doctor who may not fall within the non creamy layer if he is promoted to Group A category before completing 40 years.
Since your father got promoted to Class B that too at the age of 46 years and and also your mother joined as Group C employee, you are eligible for the privileges that are available for OBC non creamy layer category.
You may have to apply for the said certificate with the Tehsildar within your residential jurisdiction.
Their salary income, being government employees, will not be taken into consideration for computing the annual income of the family.
Also the income from agricultural land also are not taken into consideration for the purpose of family's annual income.
Your parents salary certificate may be attached to the application but remember that if the Tehsildar stick to the income whether salary or otherwise, you can prefer an appeal before the district collector on your application being rejected.