The boss's mother died. How to write short messages?

This kind of thing can't be solved by texting, and texting is not very appropriate. Because it is not a happy event, congratulations can be expressed. There is no need to send text messages to comfort.

The best way is to go there, say something comforting in person, or ask if you need help.

If you can't go directly, you can also call and ask, which is more sincere.

Someone in the unit should arrange such a thing, and just follow colleagues to express their feelings with ceremonies.