Nonessential Elements After a Conjunction

Hey there!

I'm currently editing a story for a friend, and I've come across a few instances where he has used nonessential elements immediately after a conjunction, which leads me to my question. Should these nonessential elements be set off by a comma after the conjunction as well as at the end of the element, or is it sufficient to only have a comma at the element's end?

I'll provide an example for clarification:

A) Maybe John could have gotten a sense of things if he could see, but, with the darkness, he couldn't even tell if he was where he'd been before.

OR

B) Maybe John could have gotten a sense of things if he could see, but with the darkness, he couldn't even tell if he was where he'd been before.

Personally, I've always done option A in my writings, due to my understanding of there being a pause after the conjunction, but I figured it couldn't hurt to get some outside opinion before I go through changing things.

Thanks,
Expoh