Dawn - so glad to hear that she is doing well after her surgery. As a 'veteran' of many surgeries, let her go very slowly. She probably felt really good the last day or so in the hospital, but being home is TOTALLY different. I would be up and around and visiting and doing lots of stuff at the hospital, go home and the first full day was awful. I have never felt as tired as the first full day at home after being in the hospital.
As stated above - keep her moving. Slow, steady and consistent. One more step each day. One more up/down than before. When I had both of my knees replaced in the same surgery I worked my butt off - rehab and otherwise. Push her/yourself a little each time. But when she is tired she has to rest. The PT told me that you need as much rest time as activity time at the beginning.
Blessing and prayers to you both. How wonderful that you are there for her.