Ulrich and Theraposa both see Fiona fall and then disappear, along with Apollodorus' body. They also both hear him shout out a warning to Fiona to remember the staff and it being useful to get back home. The also heard the things he'd said previously, about the book, House Guernicus and Laetitia.
((Peregrine, look in this thread to resolve what happens to Fiona.