It sounds like your cousin may be eligible for a dependency override because s/he does fall int he following categories:
parents lacking the physical or mental capacity to raise the child
parents hospitalized for an extended period
Student needs to work with HS GC, Social workers, and dad’s caseworkers to gather all documentation to support the over ride. As@mommdc stated the most student would get is a PELL Grant and an increased loan. It is not guaranteed and each school makes its own determination and the override would have to be done each year.
I hope that this helps in assisting you/your family in assisting your cousin: