What is the best treatment for osteopenia?

Here's a few. Weight bearing exercise, sunlight and vitamin d3, vitamin k2, and calcium will all help your bones. Too much meat and sodas can also cause your body to become acidic and cause the calcium to leach out of your bones to buffer the body's pH level.
Depends. It depends on the severity of the osteopenia and your other risk factors for fracture. You want to make sure you are getting enough calcium and vitamin d. Weight bearing exercise also strengthens bone and prevents falls and fracture. Quitting smoking prevents bone loss. The need for medication will depend on your other risk factors and the best med for you depends on your other medical conditions.