Recovery time for a broken hip after 8 weeks of bed rest?

Depends on how fit she was to start with, and on what has been done in the way of PT while she's been bed-bound, and on how determined/willing to work she is, and so on and so on.

Mobility good enough to return home: depends how accommodating her home is for someone with impaired mobility. Having said that, last week I went to visit a recent leg amputee living alone in a 400 year old multi-level cottage halfway up one of the Brecon Beacons, wheelchair bound until his prosthesis is fitted; and his attitude is that he'd rather be shot than stay in respite care like his son tried to arrange for him. You'd be amazed at how inventively people find a way. He was doing fine. My poor little car will never be the same again though.

When my mother fell and fractured the femur where it joined her knee replacement at 86, she couldn't bear any weight on the knee for 6 weeks but she didn't stay in bed. We used a lift chair and Mom would stand and use a walker for balance as we changed her clothes and incontinence panty or washed. We did a few very basic movement exercises while she sat in her chair like flexing her ankles and picking her leg up by lifting her heel, moving her leg side to side, picking her foot straight up off the floor, extending her leg from the knee, turning from the waist, and lots of arm movements. When she started PT, Mom was able to take steps with the walker immediately, but was initially limited in her progress because a damaged rotor cuff meant she couldn't place as much weight on her arms as she needed. It took 2-3 months, but Mom got back on her feet although she will always need the walker going forward more due to her spinal stenosis than to her knee injury.

Why was she on bedrest?

Was this a broken hip only or was there another break involved as well?

For the record, after my mom's surgery for a fractured hip at age 90, she was out of bed and bearing weight second day after surgery.

Weeks of bed rest without any kind of PT at all? I agree that is very unusual and the loss of muscle tone will likely be difficult to overcome. A lot will depend on your grandmother's overall health and her determination to succeed, but at her age any progress would usually be much slower and harder to attain. Actual weight bearing, even if only for a few moments, makes transfers possible and can make it possible for her to return home with support. My mother pretty much lost her ability to walk after a 2 week respite stay in the nursing home (I was unaware they could have done PT during her stay), it was possible to care for her at home with the help of a good tilt in place wheelchair and an accessible bathroom and shower, but it was a full time commitment.

Obviously I don’t know your grandmother’s medical condition but normally people who break a hip are given therapy and are encouraged to be back up pretty quickly. Weeks of bed rest are more unusual now. Hope you can get with a physical therapist and get some good advice soon

This is hard to say. Breaking of a hip is serious in the elderly. I don't think anyone can answer that until she has had therapy for a while. There will be care meetings where this question can be answered. You may be able to go with Gma to a therapy session and ask the therapist then how Gma is doing.