The former. Beric is dead for good in the books, and not coming back. 

Here’s why I think it’s safe to assume this: 

• in the post-episode bits and interviews about the show, the showrunners have made a big deal about needing the dragon to die then working backwards from there and hitting on the rescue mission. 
• as we’ve seen with Craster’s Keep and Hardhome (and sort of the Battle of the Bastards, although that’s more a mix of this phenomenon with the Battle of Ice from the books), the showrunners really like doing action scenes with Kit Harrington and will invent stuff out of whole cloth to make that happen.
• the Wight Hunt had a lot of similarities to some of those invented scenes:
• they involve a bunch of named characters in a situation that would normally involve a huge body count, but only redshirts die (except for Thoros) so there’s no real impact to the plot, as far as characters not being alive who they need to do stuff later. 
• they are often circular in terms of motion: Jon goes to Craster’s Keep and then comes back to the Wall, Jon goes to Hardhome and comes and then comes back to the Wall, and now Jon goes to near Eastwatch and then comes back to the Wall. This way, rather than leaving our protagonist in a new location as their status quo (like Dany capturing Meereen), the main characters are back where they need to be to do the rest of the plot. 
• they often involve some impressive spectacle in terms of CGI: Hardhome gave us lots of wights, this gave us lots of wights plus dragons, so it’s an escalation from Season 5.
• It also involves a lot of characters who are unlikely to be in the same place at the same time in the books. Sandor is at peace on the Quiet Isle, Beric’s dead for good this time, Thoros and Gendry are with Lady Stoneheart whose plot was given to Arya, Tormund is at the Wall, Jon’s dead, Jorah is still in Essos. It would be very awkward indeed to get them to the Wall together while everything else is going on in time for this mission.
• Finally, the whole get-a-wight-to-convince-Cersei thing won’t work with how the books handle the wight rules. In the books, wights stop reanimating when they get south of the Wall and rot away into nothingness. While the show dropped this storyline in Season 2, in the books Alliser Thorne is sent on a mission to convince the Iron Throne of the threat to the Wall and fails.