Mourning friend whom I have seldom seen lately

One of my former highschool classmates lost his sister to illness earlier this week, after having lost his father three years ago. I would like to comfort him somehow, but I don't know what I can do (or if I even can do anything).

Some context:
We were not particularly close during the school years, but there was friendliness; and, after school ended, we sometimes saw each other, together with other common friends/acquaintances. In these last six years, I've seen him kinda rarely, usually during hangouts with another ex-classmate. We keep in touch by occasionally sending each other stupid shit, or talking about frivolous things. I feel he's a good guy, but I never built any kind of close friendship with him before (because I was completely unable to do anything like that), so there isn't any real familiarity. Despite this, when he phoned me to tell me his sister was going to die, I told him that, for what it's worth, he could've counted on me in case he ever wanted to talk, because I didn't know what else to say. I feel I can't even say stuff like "Hey, wanna hang out?", because never were that close before, so it would probably sound strange; also, he has his own life (work, fiancée), and seeing someone is not as simple as it could've been when we were 20.

Do you think there's something I can do, in this scenario?