When looking at the pictures of the yellow cup(s), I noticed that the hospital meal was on the table, a pink-colored domed top and cup. It's very unusual that those items would have been left over from the evening meal, they're usually picked up from all rooms. Wouldn't be surprised if HKS requested a "Do Not Disturb". Or, were they from breakfast?
My mother used to keep things from her tray for later so I don't find that very unusual and because they were up so late, she might have requested something. They usually have a fridge on the floor and will give you anything they have that isn't restricred by your diet and there are hospital vending machines....Which made me question Howard's trip to start with. He didn't exactly bring back a gourmet meal.
That means that the nurse would have seen Daniel UNLESS Howard heard the cart and went to the door and said "I'll take it. Anna's still sleeping". It should be memorable to whomever delivered breakfast that morning.
I realize that you were talking about breakfast the day BEFORE Daniel died but I wrote about the day Daniel died.