When and why did Germany surrender to Europe? At what point did the Allies officially win?

This question does not make sense. Germany has never surrendered to Europe, neither has it been at war with Europe. Europe is geographical term for a region of the Earth not a political concept such as a country. The second question leads me to believe you are asking about the second world war, although you have not made this clear. I will answer on this assumption. The German government of the Nazi regime surrendered to all the allied nations on the 7th or 8th of May 1945, depending who you ask, it makes no practical difference, It did so because it was utterly defeated on land sea and air in every theater of the war and every square inch of its territory was occupied by the forces of the allied nations. Of course the allies were still at war with the Japanese empire until it too surrendered on the 15th of august 1945.