As far as words, the most comforting to me was always "I don't know what to say, but I'm here for you, and I'm going to be calling for the next xyz days if that's okay with you." That way I knew they cared, and that they were there if I needed to talk, and that I wouldn't have to pick up the phone and dial.
The most thoughtful gift I got was a small linen-covered box, with 4 small picture holders on top. The shirt I wore to mom's funeral, mom's favorite shirt, the program-thingies from her funeral, some of the cards, the CD with the song she picked, and a few other things are in that box. Its a box small enough to be out in the open, discreet enought to have out without making people uncomfortable about what could be in the box, and accessable enough for me to go through whenver I need a moment to grieve.
Mom to Lala (2004), Bonus Mom to Big Sis 1 (1991) and Big Sis 2 (1992)
Grammy to Big Kindy Kid (2011), Big Pre-K Kid (2012),
Grandbaby Appendage (2014), and New Baby Grandboy (summer 2017)