The correct use of punctuation with a subordinating conjunction is:
Because of you, I was able to get the help I needed.
However, note that "Because of you" is a prepositional phrase, not a subordinating conjunction. A better example of a proper use with a subordinating conjunction (like "because") would be: "I got the help I needed because you offered to help."
From the options given, the first choice correctly uses a comma before the main clause.