I have an employee that emergency surgery about two weeks ago. the main boss wants to fire her because she?

hasn't came back to work yet. she hasn't ben released by her OB he want to fire her because she hasn't communicated with him about her leave. I am her manager but he is stating that by her not coming back in as of yet that she is in a way giving a resignation. How can I avoid from her getting fired? I know that he is wrong and even though i keep telling him that's incorrect he is persistent that she is resigning. HELP