What to write for condolences on the loss of a younger parent?

A co worker (25yrs old) lost his mother to Lou Gehrig's disease. I don't want to say the same thing as everyone else, Sorry for your loss, or You're in my prayers. What is an appropriate sentiment.What to write for condolences on the loss of a younger parent?
Did you know the woman personally, or anything special about her (hobbies, collections, etc., especially ones you might share)? If so, you might want to throw in a happy memory or something like that. If not, his thought that YOU thought enough to send condolences will probably serve.What to write for condolences on the loss of a younger parent?
For a co-worker, ';sorry for your loss'; is about all you can say. What else is there? You can suggest that if they need anything, you are available, and offer to bring them meals if they need some help getting by. YOu can also consider taking up a workplace donation to help them handle the financial strain or show your support.