I believe very strongly in journaling as "twitter to yourself". Things you would say over messages to a partner or something can be notes to yourself instead. Especially short term desires to tell someone something can be lightened by this.
For social generally though, I would suggest very strongly that you pickup something like an MMO or a game with a community that isn't offset. Games like Path of Exile (1) or OldSchool Runescape can eat a lot of time and still give you social connections, which can help get your mind at ease from being alone. I don't suggest exclusively single player games or things like that, though.
As I said below, online gaming/interaction is probably not the best way to go. After all they are already working from home on a computer, so in a way it is more of the same i.e. sedentary without face to face interaction.
Not saying computer gaming is unenjoyable, just that they need some other things in their life.
1st paragraph is excellent advice. 2nd is terrible advice.