70 years male with stomach cancer metastasized to liver and bone, is this a good chemo drug combination (capecitabine+oxaliplatin+zoledronic acid)?

Yes: Given your age and the areas of disease involvement, it seems like a good drug combination.

Chemo : If you can tolerate capecitabine, the regiment will be good for the type of cancer. Also, consider to check her2-neu receptor status of the cancer - as if her2-neu receptor is positive, Herceptin (trastuzumab) which is an inhibitor to the her2-neu receptor should be considered as one of treatment options.