The doctor says I have dropped bladder and prolapsed uterus. What is the most effective surgery?

Many options. There are many options. Many consider sacrocolpopexy the gold standard with failure rates below 10%. Many surgeons have reported excellent results with vaginal approaches. Both using non absorbable mesh. Still other surgeons report good results with traditional repairs, native tissue, despite literature suggesting high failure rates, 40 to 50%.
Uterine prolapse. There are several methods of treatment. It depends on whether you wish more children. These include a pessary to hold things in place, or surgery.Surgery can be a "sling" operation, or a vaginal hysterecvtomy and bladder repair. Depending on your circumstances, i think the latter would be the most effective.