Sorry Meister, if you finish in the top 5 in any B or B/C class at the previous national, you are not allowed to compete in a B or B/C class the following year. As far as getting a Pro license, you have to go to the selected AMA Pro / AM events and collect enough points to earn your pro license throughout a calendar year, or finish in the top 20 in any of the 3 "A" classes at Loretta Lynns. Here's the rule from MX Sports Supplemental rules for Loretta Lynns:
3. Riders in the 250A and 450A classes are eligible to compete in the Open Pro Sport class. The Top 20 overall riders in the 250A, 450A and Open Pro Sport classes at the National will be eligible to obtain an AMA Pro Motocross License in the current and next year without further qualifications.
So if he rides B all year through Loretta's, he can run "A" afterwards and start his process of getting his Pro License in 2014. If he wants to get his Pro License after Loretta's this year, his best bet would be to run the A class this coming year and finish in the top 20 at Lorettas in the 250A, 450A, or Open Pro Sport Class to get it without having to do anything else.