As others have said, being there for them is all you can do. But when people are grieving, they may not know how to or have the energy to reach out. So check in with them every few days.
If you can get together in person, have a coffee or a picnic or watch a movie. Someplace where y'all can just sit in a space together with no pressure to talk.
@tyghebright @0x56 Or, if they are knee deep in funeral arrangements, offer a store run on their behalf, or similar mundane tasks.
Sometimes a hug and understanding is good and enough. Let the grieving party dictate conversation paths if you are together.