We are not bound to accept EXTRAORDINARY measures...but do dialysis and blood transfusion qualify as extraordinary? Both were mentioned. These are common procedures.
Also the OP mentioned the hospice worker. Why is he in hospice care? There must be some other diagnosis that puts him in a place for the terminally ill.
As for the scapular...the promises were for those envested in the scapular
who lived the conditions attached to the promises. It's not a lucky charm.
Encourage your grandfather to offer his suffering/condition in reparation for his sins, the souls in purgatory, for the conversion of sinners (especially his descendants) and for those who do not have anyone to sacrifice for them.
As his grandchild you can use the sacramentals of holy water and blessed salt to keep the devil away from him so he doesn't despair. Sprinkle him and his bed with holy water frequently and encircle it with the blessed salt.
Pray

and remember to be in a state of grace when you do.
If an when the time comes don't forget the Prayers for the Dying that Matthew has posted in the sub forum SACRED