Help please? what is the best medication/drug for rejection?

Depends: It depends on what organ is getting transplanted and how likely the recipient is going to have a rejection episode and what other medical conditions the patient has. For example, for a kidney transplant, most patients are going to be on 2 or 3 anti-rejection meds and they will likely include tacrolimus (Prograf) and mycophenolate (CellCept (mycophenolate mofetil) or Myfortic).