Wake/Visitation

Hi all… Recently, my friend’s mother passed away. We weren’t really that close, but we had known each other since 1st grade (in 10th grade now). I feel like I should do something, the wake is today. Would it be proper for me to go? In other words, how close do you have to be to attend a wake? Also, what should be worn? Are you supposed to wear all black?

Sorry for asking here, but I don’t know where else to look…
Thanks.