Adult students are lucky in Florida that you can still attend adult
school to get the credits to earn a traditional diploma. This is not
the case in other states. I know that the Florida Legislature has made
this more expensive, but even still, adults in Florida, at least,
have the choice. Go to this directory of adult education to find your local adult education provider. In some counties it is the school system. In others it may the local (used to be called community) colleges. Ideally adult students would enroll in a class and work with a tutor too. This provides more intensive instruction but is often not feasible.
It is up to the volunteer literacy program and individual tutors to help adults achieve goals. If that goal is getting a diploma, tutors should introduce adult students to their local adult education provider. Even better, introduce them to the teacher in their neighborhood. We all know that it is the people that make a difference.