Letting things out naturally was probably the best way to go about it. It someone forced themselves to respond to some, to try and make sense of something senseless, it just made it worse. At least, that was Ziva's opinion on the matter. And she was at least able to follow along with the rambling of feelings that Abby had. After seven years, Ziva was well versed in Abby's rambling. It no longer confused her or made her head spin from trying to keep up. She just followed.
The basic issue was not knowing the outcome as well as fear. That made sense. The team was their family, they were around one another constantly. They bickered and bantered. Not knowing how loved ones were was the worst feeling in the world. And that was something that Ziva couldn't help with because they were from the same point, only different locations within the building. And it was something that worried Ziva if she wasn't focused on something else at the time.
Nor could she help with the attack on the complex, on the fear of a bomb going off in the next room. It was highly unlikely but that didn't make it impossible, so all Ziva did was nod to show she was following along. Because she had no idea what to say, no idea on what would help in a situation like this. Letting Abby get it out seemed to be the best course of action so that was what the Israeli woman would do. Just give her someone to talk to who had been there. It was about all she could do, really.