lots of 80 year olds recover fine....
Ellen-
Hopefully by now your Mom has had the fracture tended to; keep us posted on her recovery.
The first thing is while in the hospital keep an eye on everything- make sure they are giving her the correct medications, getting her out of bed as soon as possible, getting her a bedpan promptly, etc.. Hospital care sometimes leaves a lot to be desired, so a family presence is a huge benefit. Make sure you keep her mentally active- this can be an overwhelming experience and sometimes even very competent elderly start to get a little fuzzy when something like this happens.
Also- if it is a non-surgical case she likely will be immobile for a longer period while the femur heals. Make sure they give her therapy so that her other muscles don't get weaker. Lying around in bed is a big risk factor for the elderly and they can weaken a lot in only a few weeks time. PT can help her retain her strength in her other leg and upper body.
Make sure she participates in her rehab. to the max and if she goes home she should get home care and home physical therapy. The therapist will leave an exercise program and the more compliant she is, the faster her recovery will be.
Don't let her get discouraged. If they had to do surgery, as scary as it is, the recovery will usually be easier. I have had dozens of hip fractures and hip replacements that return to a very active lifestyle. Even if she can't play tennis at least in the short term, there are plenty of other things to do and don't let her get frustrated. Tell her that she will likely be miserable for 4-6 weeks, and then sometime in the 4-6 week mark she will wake up one day and feel so much better than the day before. I know it sounds corny, but it really is what generally happens.
Just keep emphasizing that the walker and the limitations are temporary, and her recovery depends in part upon her motivation and compliance with doing her exercises. Keeping her outlook positive is a big help.
Good luck!