When you speak with her surgeon take a list of questions with you. The surgeon will most likely want a preoperative clearance by her primary HCP for advice on the medications etc.
There are probably as many different total hip protocals as there are total hip surgeons, and many tasks will depend on what hip system is used and what type of incision is done. Does your Mom still walk alone or does she require a cane, crutch or walker? She may have to relearn her gait when she gets the new hip because after all these years of degeneration that leg is probably shorter, and certianly more painful than it will be post-op.
I like this site for general information.
(just the hip section obviously).
As far as heparin, it has a short half life and can be reversed with medication if her PTT is too long. Ask the surgeon what and when the post op anticoagulant will be started. Ask the anesthesia provider what type she will have. I favor the epidural, but then there are certainly other options.
Find out ahead of time if her insurance covers rehab facilities.
Ask for a social work consult to help with discharge planning....that's what they're there for.
Good luck to Mom she certainly is lucky to have a wonderful daughter.