No comment on the choice to cremate, but I can on the diagnoses. Medically, this does not sound odd at all. Advanced cancer may lead to broken bones for a few different reasons. An obvious one is when the cancer metastasizes to a bone, so the bone is weakened and can easily break.
IIRC, she had a hip replacement, not 'just' a broken hip. That seems an odd surgery for someone near the end with cancer.
Put a weakened patient through a grueling surgery, that just might kill them, to provide easier locomotion in their final days if they manage to live long enough to get through the painful physical therapy so they can walk again.
You watch and see just how many terminal cancer patients get a hip replacement under 0bamacare!