Having been a professional psychologist running a Christian Counseling ministry for many years may I caution you about just having a set of scriptures to dole out. I have had to put together too many folk whose faith has been damaged in this way.
Do not misunderstand. I believe that God can and indeed does use scripture to bring comfort but when someone is mourning they do not want pat answers. They want to know that you are there for them. That you care about them. That God loves them. Frequently more is accomplished by just sitting with someone who is morning than trying to offer answers. As you spend time with them and pray for them (even when you are not with them) the Lord will bring appropriate scriptures to mind. Those are the ones to share.
I hope this helps. Bereavement counseling is a specialist area of ministry but we can all show genuine love and concern for those who are mourning.