I know how hard it was to lose my father when I was a fairly young adult - so I can only imagine how you and your family are feeling right now. You are in my prayers.
If I think about things I'd want to say to my (now young adult) daughter, if I had been in your shoes at the point in time you're currently at...
I have no geek advice, but - tell her you love her. Tell her you're proud of her, no matter what she chooses to do with her life. Tell her to take her time with boys - they'll still be there when she's ready. And tell her to tell her mother she loves her and that you love her.
Tell her about funny stories, and the interesting things you've seen. Tell her about your friends growing up, and the mischief you got into. Tell her about your favorite music, so she has something to roll her eyes at.
And take care.