If it is MRSA, then the prognosis does not appear very good.
I just got back from my uncle's funeral. He was 81 years old and was in perfect shape until early Dec. 07 when his bone adjoining his hip replacement broke. He had a replacement operation and had to have a second operation 2 weeks later, just before Christmas. To make a long story short, after weeks of grogginess and a MRSA infection that arose due to the prosthetic parts or the cement, he passed away. He was on a ventilator and could not breathe on his own without it being extremely labored.
I am glad your mother is still conscious. Unfortunately, by the time I went to visit my uncle he was unconscious and I did not get to say my good-byes. Ask your doctor to give you a truthful assessment of your mother's prognosis.
For an example of the severity of MRSA see http://www.journals.uchicago.edu/doi/full/10.1086/313658 , which describes a high mortality for liver transplant patients.
The impression I have is that a large percentage of those infected with MRSA succumb.
Pneumonia due to methicillin-resistant staphylococcus aureus (MRSA) infection of the lungs can be life-threatening, especially in the elderly, but recovery is possible, especially if your mother has never smoked and heretofore, had healthy lungs. Assuming that she is receiving intravenous antibiotics, either at the rehab center or the hospital, whether she is to recover or not should soon be evident by clearing or worsening of pneumonia.
You should be in close contact with her doctors, on a daily basis, to discuss the likely scenarios and consider your responses to each. If her doctors believe that she may yet recover and her appearance to you supports that, then therapeutic efforts should continue. If she recovers from the MRSA, it is likely that she could experience a quality of life, not dissimilar to that she had prior to the hip fracture, especially if the repaired hip allows her to again to become even semi-ambulatory.
Good luck.