(a) Subject to subsection (b) of this section, the court shall have jurisdiction to enter guardianship order and shall retain jurisdiction to enforce, modify, or terminate a guardianship order until a child reaches 21 years of age; provided, that when the child reaches 18 years of age, the child consents and the court finds it is in the best interest of the child.
(b) A child who exits foster care to guardianship may not reenter foster care after age 18.