If your mum survives the trip and survives the weeks after they need a new way to be handled

they have to be assertively told what to do and when, even supervised

they have shown they are incapable of making choices

and your mum is asking to be told, asking to be looked after,

I suggest a home visit nurse but first can you contact the ship’s doctor? I’m sure they would appreciate a head’s up rather than having to deal with a health emergency on ship