It's a stalemate because your opponents king is not in check and your opponent has no legal moves. If you're not giving check in this sort of situation you must make sure you leave your opponent's king a square to go to.
Instead of c5, play Qd3, and after Kb4, either queen to a3 is checkmate.
55. Qb7 is also mate, you didn't need to chase his pawn, if you leave the pawn you also wont stalemate him by accident.
Would someone look at my game that was stalemated recently and explain how.Im not understanding this and its happened twice.Ive tried to read up on it in the one book I have however Im just not understanding or know how to avoid.What move should I have done?