If you're wondering how to be of help to someone who has had a death in the family...
maybe you can be a point person -- writing emails, and calling people, so they don't have to discuss the same story over and over...maybe you can pick up stationery for notes or even help write the notes...I wrote an obit column for a magazine, so I have written 7 obits for friends over the years so their family didn't have that to deal with.
Think of how you would feel someone could be useful to you -- then you will have your answer of how you can help. Think outside the box. It also could be as simple as a bouquet of flowers or a plant they can keep to remind them of the beauty of life and how it continues, or a really great bag of coffee or chocolates to pamper them a bit, nice massage oil or bath salts, or something unique to you or your friend you share between each other.
Don't write or tell someone 'if there's anything I can do, please let me know.' That is well-meaning, but frankly, it's pretty useless. It's not up to the person to tell you -- even the closest of friends can hesitate to ask for something. Asking for things is difficult.
If you are afraid of writing for fear of saying something wrong, simply write how sorry you are for their loss, and how they are in your thoughts and/or prayers, and that you'll call and email soon to see what you can do - and for them to be thinking of how you can help.
Remember, nothing's more important than knowing their loved one was important to others. Hearing how their loved one had a positive impact or recalling a funny story or piece of advice is something they will treasure, and keep or remember.
What's painful is when they can't mention their loved one. People fear bringing up their name or memory will be painful and they try not to mention them, but what can make them sadder is having people not mention the huge void in their life. They crave talking about their loved one, and want to keep their memories alive as time goes by.
There are many ways to create 'living legacies' -- donate in their name to a charity or something they were invested in or loved. Plant a tree. Or just live in a way that honors their life or way of living. You don't have to go "Newman's Own" big -- you could change a habit for the better and tell the family how their loved one inspired you to make the change. Or tell them you had a medical test because of their experience.
Any act of consideration and kindness is appreciated and makes the world a little kinder than before...we are all connected.