Changing care facilities is always an option; you are not required to remain in a facility just because you started there. If the care your mother is receiving is not
adequate, then you should definitely look into finding another that would provide better care.
Before you do that, make an appointment with the head of physical therapy and ask questions. The department head may not realize that her care has inadequate. There is a device called a 'Hoyer lift' that can be used to transfer heavy patients. Are they using one? Are they aware that she is a 2-person assist, and do they have adequate staff to care for her?
These become the questions you ask at an alternative facility. There is no point in moving her from one place to another unless you are certain the new one can do a better job. Talking to the head of PT may help you understand why your mother does not seem to be recovering as you expected. Between one third and one fourth of older adults who break a hip never regain the ability to walk again unassisted. Due to her weight, this may be the case with your mother.
There is NO reason why she should develop bed sores. Sometimes bedbound patients get them on their heels; these are harder to prevent. But bed sore on her hips are usually preventable by frequently changing her position and getting her into a chair from the bed. Again, ask someone in charge of care about this. If your mother is refusing to get up, then she will have the same problems in the next facility that she is having in this one.
If your mother is refusing to participate in rehab activities, she probably will not confess this to you. This information you will have to glean from asking the therapists in charge of her care. Rehab from a broken hip is hard work, and requires effort and commitment from the patient as well as the therapy staff.
Get the facts before you make a move, and if you must move her, be sure the new facility understands the problems and believes they can do a better job with her care.