Can my Politoad learn Mud Bomb via Heart Scale since Poliwhirl learns Mud Bomb at Lv. 53?
No, because according to Politoed's Pokedex page, Mud Bomb is a pre-evolution move.
This means you can't teach it mud bomb via giving a heart scale to the move relearner, as only moves that the Pokemon learns by level up can be taught this way.
So if you want a Politoed with Mud Bomb, you would have to level up Poliwhirl to lv. 53 (or Poliwag to 41), teach it Mud Bomb then, then evolve it into Politoed. Also, you can have it learn Mud Bomb through breeding if both the mother and father know the move.