hmm I'm not sure, all I remember is that Philippa said that Cynthia (the leashed sorceress who betrayed her) left something and it might've been the rose of remembrance? I don't know, how can I find out?
rose of remembrance is what she leaves behind.
the immortelle- i usually find about 12 of them in that cavern
the dragons dream crystal from inside the harpy's lair (not the bomb). make sure you view the dream crystal via the viewer in the cavern to id the crystal. as there are several dreams in the lair.
I forget the other item.
My guess is that either you're missing one item still, or need to speak to someone still. I can't remember if on having the 4 items she says meet her there, in which case the elves will have moved slightly away from the center of the door, or that telling her initiates a cut scene.
I always had the option to tell her I had the immortelle, even after I told her, but it wasn't until i had all four did she actually give an option on having all the components, but the immortelle dialogue option always stayed up.