Christmas card etiquette

I would get a Christmas card without printed words and write thinking of you at this difficult time or similar (((hugs)))

I would just say Thinking of you at Christmas .

Season's Greetings?

Thinking of you and wishing you a gentle Christmas.

"Thinking of you" is what I would choose, although I couldn't find one I liked recently and so sent one saying "Wishing you a peaceful Christmas" to a family who have someone who is very ill just now.

It's probably more important to actually send a card than to get what it says exactly right, as I would think that some people might feel too awkward to send one at all.

I have a friend in a similar situation, I sent a card with animals in the snow, It was blank inside and I said I was thinking of them and their unfortunate situation at such a difficult time of year for them.
I got a phone call to say thank you and it was good to know someone appreciated their situation.

I used to work in retailing greetings cards - there are plenty available which say ‘Thinking of You at Christmas’ with appropriate words/verses/blank for such circumstances.