A question about Medicare A & B......

I have a question regarding 2 insurances.  One is Medicare and the other is AmeriBen.  AmeriBen is my primary and Medicare is my secondary due to the fact that my husband does work and we have insurance through his job.  Now the policy that we have with AmeriBen, the employer has made a clause that states that only the employee can have the surgery not it's spouse or children.  I have talked to Medicare and they have told me that they will pay in place of my primary insurance (AmeriBen), meaning 80% leaving me with 20%.  My real question comes in here:  I have Medicare parts A & B, meaning that they will pay for the hospital stay, just not the doctor.  (It's either part A or B, I do keep forgetting) Will Medicare still pay for the entire hospital bill even if they are paying 80%?   I hope that this question comes across clearly......

I don't know if this will help you but this is how it worked for me. I am on SS disabilty. I chose to only carry Medicare part A when  I was awarded my disability as my BC/BS FEP provided me better benefits than Medicare part B.  Medicare part A paid all my inpatient expenses and was considered my primary for this hospitization. We have BC/BS Federal Employees (BC/BS FEP) that covered all my outpatient charges except for the 10% that I had to pay. I am assuming that Medicare A  covered my surgeon's fee as I have never received a bill form him. Hope that helps? Gena