Which of the following is most effective in enhancing remote employee's wellbeing?

I think most people appreciate WFH because of the flexibility. 

Virtual Happy Hours can get awkward unless they're very intentional. I like the idea of book clubs and other opt-in, interest based connection opportunities. 

We also use "donut" for random bi-weekly coffee chats and it's a nice touch. 

Flexibility is key. Understanding that people have a life. Work makes up part of life but is not the same thing for all people.

Meeting their needs as a human is so important. Most people desperately needed a little more flexibility over where they work and when they work. That's an easy win. After that it's about giving clear goals and expectations and as much autonomy as they need.