Welcome to the world of presumed guilt. It used to be they had to prove you guilty, now it's turned, and you have to prove your innocence instead.
I'm sorry to hear of this Donuel, and can't imagine how upset your son must have felt.
School's gotta do what the school's gotta do, but it sounds to me like the social service agent made it worse by not following up diligently enough.
Apart from anything else, they left a child in a home where they thought he was being molested, and had it been true that he was being abused, then what they did was criminal. Imagine what could have happened to an abused child in the time that has elapsed since the original accusation.
Like Bobert says, get yourself a lawyer my friend.

Giok