Really impossible to say without knowing your exact situation. But, fifth year aid is usually awarded to players who have exhausted eligibility and have 30 or less credits to graduate. Generally speaking, it is up to each athletic department to choose how much they fund the student-athlete for the final year. Some big schools just automatically pay everything. While, some smaller D1 schools have to "ration" out the aid and divvy it up to student-athletes they determine most in need.
In general, the student-athlete has to apply and the coach, AD, and another admin member have to sign off on a form(s). The players who usually get in a fifth-year aid situation are international kids who come in January and really have no reason to play their last fall (without being able to play the dual season).
The thing that puzzles me is that your kid is playing at the NCAA's (individuals, I am assuming), which means not only is he probably playing for a big school, but is damn good. The first person that anyone would ever talk to about fifth-year aid would be their coach (then maybe an Assoc AD of Academics support for Athletics). So why haven't they talked to the coach??? The only reason a coach wouldn't sign off on fifth-year aid would be if the player was a total a-hole and was behind in credits for not going to class...or some similar situation where the player had done something seriously wrong. Why would a coach or athletic department not want to help out a stud kid who made the NCAA's as well, assuming he/she is a good kid?
Without doing a redshirt or medical redshirt, the only reason you would usually be behind to graduate would be if you took a lighter load to focus on tennis or if you had trouble balancing the two. You could do 24/48 for your first two years and 60 credits is full time. Take a look at this link for progress toward graduation. http://www.uiowa.edu/~athlss/current...ligibility.htm
So if he/she has done 8 semesters and is in good academic/athletic standing, I don't see why there is an issue.