Hi Hought,
I think it would also be good if you can take your grandmother for lower back and hip MRI. I work with the older population and my mom is also an elderly woman.
It is up to the Physio to decide plan, or pathway of treatment, but by the little info you gave, I would do 3 things: 1 hands on physio... Dry needling, miofascial release and massage maybe 2 lots of weight bearing exercises, transfer Ed, core stab program 3 walking exercise program maybe with assistave device.
Hope it helps