Aish's site had the clearest instructions:
The seventh and final day of shiva is observed for only a few short hours, although this counts as a whole day. After the last Shacharit service, the mourners sit low again for a short time. Then those who have come to comfort the mourners say to them, "Arise." The comforters then say:
No more will your sun set, nor your moon be darkened, for God will be an eternal light for you, and your days of mourning shall end. (Isaiah 60:20)
Like a man whose mother consoles him, so shall I console you, and you shall be consoled in Jerusalem. (Isaiah 66:13)
The mourners acknowledge that the shiva is over by leaving the shiva house publicly for the first time, taking a short walk around the block with those who have come to comfort them.
So, that's what we did. And then I walked her back to her door so she could back to her life.