A bundling denial, CO-97, would indicate that the denied service is inclusive to something else that you have billed for this date of service, which could be either on the same claim or on a separate claim. If there is no other code billed than these two, then I'm not sure what this would have bundled to and you may need to contact the payer to find that out.
The CO-151 denial indicates that the number of units you have billed, either on this one claim or on a range of claims over a given period of time, exceeds the number that is allowed for a patient for that period of time under the payer's policy. I'd recommend starting by verifying that the units you've billed is correct per the documentation of how much drug was administered. If correct, then you'll need to review your Medicare contractor's LCD and/or NCD policies to determine what their limitations are for this drug, and whether or not the dosage given is actually covered under the policy.