A week after the Basilisk showed up, Mira and Robin went back to descending further into the chasm. They both wanted nothing to do with such a beast so they decided to camp out in one of the caves for a week until they were sure the threat had passed.
They probably would've been fine to start their journey again after a day or two, but Elenei recommended they wait a bit longer just in case. Mira agreed with her suggestion and told Robin that it would be better for them to wait.
Although Robin was a bit worried that she would be too far behind the Branch Head, she was more worried about her life.
Now, after a week of resting, the two of them plus Rhydian began making their way down the chasm again, except this time things were a bit more peaceful. It wasn't hard to guess the reason why as they literally just encountered the beast and its minions.