48.White to move

In the position above it seem like white is in better position because it has two connected passed pawn.However Black also has a passed pawn and active pieces that pose a threat for white.The question is

a)From your point of view what is the best continuation for white to gain an advantage and lead into a winning position?

Thanks again to Eugene for solving problem 47 by 1.Rf6 Nxf6(....Rxf6 2.Ne7+) 2.Qxe6+ Kg7 3.Qxc8 Nxd5 4.Qxb7+ Qf7 white win in material and with accurate move lead to victory.