Can md force patient release from hospital rehab when insurance will approve staying there?

My mom in law had stroke Jan 29 in Lubbock TX. In hospital ran rehabilitation. MD has been wanting her to go elsewhere for 2wks. Humana insurance will only approve keeping her where she is. Humana says if she is moved she will have to to private pay and they won't cover rehabilitation not medication. Humana and MD have had 2 pier to pier by Humana request and the two of them will not agree, each wants their own way.