What is a good sum to give my best friend's son for graduating high school, and her daughter for graduating from college?

What amount is good to give my best friend’s son for graduating high school?

What amount is good to give my best friend’s daughter for graduating college?

The party is this weekend.

Also, if the son is a pot smoker (which I don’t necessarily disagree with but I do think it’s a waste of money, and even though the money is his, I would rather he not spend it on pot) should I give the check to him himself or give it to my best friend for her to determine what to do with it?