Does the biological mother of a dying adopted child have any legal blockades?

The adoptive family would have the final say if the child is under 18. The birth mother would have no legal rights to see the child. When you place a child for adoption your parental rights are terminated permanently and you become a legal stranger to that child. The birth mother would have no more rights than a stranger on the street. The adoptive parents become the legal parents and get to make all decisions for their child.