How did the titan that killed Eren's mom appear inside wall Rose during season 2? During second season (I think is called Clash of the Titans) it's shown that:


   there wasn't a breach in Wall Rose and that those titans that appeared were transformed humans from Connie's town. 


How did she get inside Wall Rose then?
If not mistaken the shifter titans tried to go back to Wall Maria and were some where between wall Maria and Rose,  which was titan territory. 

In the picture, you can see how Eren's Liberation was between Wall Maria and Wall Rose.  The smiling titan never passed Wall Rose, all that part was in between Rose and Maria.