No, the correct answer is not C. C should be punctuated with a period at the end. "I was wondering if you will be able to make it to my party." Indirect questions with like "I wonder if..." are written as statements although in informal texts or questions it is becoming more common to see a question mark.
The question that is correctly punctuated is "Can you come to my party or not?" We use a comma before conjunctions like or, and or but when we are linking two independent clauses like "I can come to your party, or I can go to James' party." However, we don't need one here between the two options as or not is not an independent clause.
The second question needs a question mark not a comma in the middle. "Didn't I tell you I could not come to your party? I could have sworn that I did."