In my own family, i lost a sister. Almost everyone felt guilty and responsible in some way, but no one was responsible for what happened. It was just a stupid accident. I think the guilt comes because we are shocked. Our world as we knew it has changed when someone we love dies, particularly if they are young and it was sudden. We are trying to make sense of it, but in truth, it is senseless. It doesn't matter if there are "reasons"... it's still senseless. And i think we feel guilty because feeling responsible is easier for us to bear than feeling like we have no control over losing loved ones and that there was nothing we could do to prevent their death.
It is hard to recommend how to help someone who is grieving, because we grieve differently from each other. When my sister died, my mom disolved into into her suffering, and it was very visible and consuming. My dad was opposite... he became very hard, and he became hard on others, believing we should all be like soldiers, and hard like him. My brother became numb and claimed to feel little, but he became numb to everything in his life. What they needed was different from eachother, too... my mom needed to be distracted from focusing so much on her grief and helped to see other things. My dad, again opposite, needed to be encouraged to focus more on his grief... to express the sorrow he was burying under a hard exterior. My brother needed to be encouraged to express the anger that had made him numb because he had buried it and pretended wasn't there.
There is one thing i have found though, that i believe will help everyone once they are past the initial shock... and that is for them to find a way of redirecting their feelings of loss. I have a theory... that we can't squelch the energy of strong negative events in our lives... we must either redirect the energy into a positive effort... or it will find a negative expression on its own. For example, some people might start drinking in response, while others might start a charity to help people.
When my sister died, it was the day before my eighteenth birthday, i channeled my grief later that spring into putting the stamps she had collected for years in a shoebox... into an album. Stamps meant nothing to me, but i loved her. It helped me feel closer to her to complete something she never got around to doing. And i started to like stamps.

I also started knitting again... which was her favorite hobby. I know that sounds like a strange solution, but it worked for me.
One woman who lost a child in a drunk driving accident, started MADD, an organization that works towards reducing drunk driving and saving lives. BellaOnline ALERT: Raw URLs are not allowed in these forums for security reasons. Please use UBB code. If you don't know how to do UBB code just post here for help - we will help out!