Su Xiaofeng's luck was simply defying the heavens.
Originally, all it would take was for Yu Shuiling to have an episode, and then with the medicine missing, they could've easily blamed the loss on Su Xiaofeng, perfect.
But who would have thought that Su Xiaofeng could wake someone up with just a few breaths of mouth-to-mouth? If it wasn't for her good luck, then what was it? If it hadn't been for her good luck, Su Xiaofeng would now be seen as a murderer from the countryside, and she might have even brought trouble to the Quan Family.
You know, Yu Shuiling's three older brothers are all sister-fawning maniacs; if anything had happened to Shuiling, they wouldn't care whose door they had to knock on to seek revenge.
Instead, Su Xiaofeng turned out to be lucky and became Shuiling's lifesaver. What a bargain for her.