1. "Things will get better."
2. "I understand your loss."
3. "Here's how we can fix the problem."
Some insight into why can be gained by watching the short video, It's Not About the Nail:
https://www.youtube.com/watch?v=-4EDhdAHrOg
In many (but not all) cases, if the grieving are willing to communicate at all, they want their cries of pain heard and listened to. They would rather that you cried with them instead of trying to tell them that there is light at the end of the tunnel or that there is a 'fix' for their 'problem' or that we must accept that life is hard and unfair and suck it up.