Having read more posts, I do think that making sure the place is extra clean, warm enough and has a very good supply of things like fresh bedding, loo roll, paper towels and so on is actually a great approach - not that your place wouldn't already fulfil those requirements!
And some basics in the fridge/kitchen like tea and coffee, milk, bread and butter, biscuits and so on are always helpful, it isn't overwhelming the guests with food that the ill person potentially can't have, just making sure there are a few basics about. They will come prepared with any special foods that are needed. Again, you may provide basics routinely anyway!
But a simple hamper could be ok too, I wouldn't overdo it though since as people said you don't want to create future expectations and there might be not one thing in it that the ill person could actually eat. Or of course they may scoff the lot 😁
A few gentle tasteful decorations like a little greenery sounds nice, but nothing over the top. I think I agree about not too many fresh flowers, since as PP have said the smell may be too strong and they require care. You could also check with the guests beforehand, say you usually decorate at this time of year and ask if they mind. They may or may not want a festive atmosphere.
Although some people would really appreciate the camera idea, there are those who wouldn't, so I might leave that alone, as it seems potentially a little fraught. They are in charge of how they want to record their time and make memories and certainly a vulnerable person may not wish to be photographed.
OP you have shown kindness in wishing to make their stay special, I think less may be more in this case but I'm sure they'll have a wonderful stay.