For the last couple of days, I've wondered what this question meant. I thought it meant that Merkel, in her position, is ultimately accountable (=responsible) for safety regulations and anti-terror counter measures during largely held events. Later it dawned on me that it could also imply the popular notion that Merkel's actions of "allowing" refugees "in" have these negative consequences, which are unavoidable - unless the opposite action is taken.
For lack of my personal view, I thought this article summed it up surprisingly well.