Esta will conjure up his Create Food and Water, and eat some of it. Of the rest, he sets aside the remainder of one man's rations for himself, and the rest for Mariona, placing his portion by a scrap of his clothing and her own portion by one of her things, to indicate which is which, if she should wake before he next does.
Mariona has had too little to eat, by the looks of her, and Create Food and Water does make enough for three. So she should have two-thirds of this food. That is simply objectively good logistical sense.
He drinks, sparingly, because he has not been told where to urinate if he feels the need.