They need to be reminded that they are not forgotten. Help attend to practical matters. Help answering the phone, addressing thank you cards, preparing meals, care of the children and house. This kind of help lifts burdens and creates a bond. If the survivor doesn't feel like talking, don't force conversation.
Silence is better than aimless chatter.
Be a good listener. Accept whatever feelings are expressed. Do not change the subject. Be as understanding as you can be. Never tell a survivor that you understand how they feel.