My honest answer is pray for them twice a day and do call them everyday just to tell them you are there for them and in you they will have a constant friend, and supporter. Because young people go through a lot of sadness too when they are all alone in the world. I personally converse to my parents like I am / or they are writing a diary. It has worked well. We haven't lost touch and we pick up right away when we meet. But physical loss is really hurting. Prayer will definitely mellow down the mourning and will give positivity to the whole situation.