They are not ENTITLED to them, but the old group's bylaws should lay out how any remaining funds should be disbursed. Most likely, they could CHOOSE to donated those funds to another parent group. Our bylaws state that they must go to a 501c3, and preference will be given to another parent group. Check those old bylaws. If they do not clearly state where the money goes, you may want to consider amending them before the group has completely dissolved.
If you have governing documents (articles, constitution, bylaws, etc.) there SHOULD be an article about dissolution. If you are a 501(c)(?) you are required -by IRS- to pass any remaining funds to another 501(c)(?).