Osteoporosis treatment options

My mother in law is 66 and was diagnosed with osteoporosis 6 months ago, but only Calcium tablets were advised then. A detailed bone density test was done now. The doctor has prescribed annual Zoledronic acid injection (Novartis ), and Teriparatide injections  alsong with vitamin D3 injections.

BMD test results:
Spine: .816 gm/cm2 T score -3.0
Forearm radius : .209 g/cm2 T score -5.7
Femur  Total Right :  .778 g/cm2  T score : -1.8
Femur Total Left :    .813 g/cm2  -1.5  
Femur Neck T score : .707 g/cm2,  -2.5,-2.1

My questions are:

1) Should oral  Bisphosphanates be preferred over intravenous ones ?

2) Will Bisphosphonates be sufficient in this case, or are Teriparatides needed ? Teriparatide injections in India are quite expensive and monthly treatments for a year will double her monthly spending.

3) A second opinion was taken from a family doctor and he suggested taking Teriparatide injections alone. Does that not seem wrong - since Parathyroid hormone will also increase resorption if calcium is deficient in the body ?

Thanks
Anir