The child did not choose her mother to be her "guardian" but this is something that was done via law. I would agree that adoption is very unlikely but is still something the mother can try if she does not wish to continue to case for her child. I do not see why you say that putting the child in foster care would not be an option. Foster care is always an option if the child does not have any family to care for them.
Agreed the child cannot choose anything and in this case will never be able to choose anything.
Foster parents make an average of $800-1000 dollars a month per child they watch. They often try to watch more then one so they can make more.
This child would require someone who has undergone extensive training on how to take care of her. Care of this child requires multiple and regular administration of tube feedings, care of the feeding tube, multiple daily diaper changes, daily showers and transfers form her bed to a wheelchair. Daily checks for skin breakdown on the buttocks and other pressure areas looking for pressure wounds.
She needs someone who will watch her and be there for her 24 hours a day. No foster parent is going to accept that for $800 a month. No responsible child protective service would put a child with this level of special needs into the foster care system where it is a guarantee she would not get properly cared for. She would need to be placed in a nursing home.
If the child is not able to make an informed decision to have her life ended then there is no reason why it should be, as long as she has not done anything wrong
EDIT: by 'anything wrong' I am anything that would be accepted by society as being deserving of the death penalty
