Craig Mazin, a showrunner on The Last of Us, confirms the recording here is a blend of Johnson’s original performance for that game teaser and “a slightly updated version” s

Though Johnson had already appeared as Ellie's mother last season, she was brought back again in 'Through the Valley', but not in the way you might expect. Keen-eared fans would have recognised the voice singing during the final moments of the episode, a hauntingly beautiful song only made better by the fact that it was being sung by Johnson.