Progressed Moon inconjunct Pluto and square Neptune seems to me the ideal aspect combination to look for (and find) shelter, but it is also an aspect combination that reveals sadness. In her natal chart the Moon is inconjunct Pluto AND Neptune.6. Mars-Pluto
There was a lot of interaction with Mars and Pluto in their charts and there were transits between Mars and Pluto on that tragic day.
Also visit: Astromarkt.net, for example