Tracy, I wish you and your husband the best with your new to you Class C.
Certainly not trying to take any wind out of your sails, But I can tell you from experience that a "gifted" 15 yr old RV can quickly turn into a money pit. A lot may depend on where and how it was stored, when it was last run, age of tires, roof integrity and general chassis and structure maintenance. Unless you have more than just basic mechanical, electrical and plumbing skills, I'd have a professional assess your RV. Under their advisement, I'd decide whether its worth putting some $$ intro it, or get rid of it. I happen to have skills in all the areas I listed above, and when I took on a gifted motor home, the parts and hours I put into it to make it useable was to a point where I was kicking myself for taking on the project.
That being said, I hope yours is in tip, top shape and you get many years of enjoyment out of it.