Well, I don't know all of the game mechanics so this was valuable information. I guess I have to place the family's I want to keep in "My households" then. I don't own many packs so I have a very low limit though. But OK, thanks.
Welcome to the forum @Madhunter
About learning Ann's cause of death, can one of your sims place her urn in their inventory and take it to their home?
If you place it on your lot, Ann will eventually appear as a ghost and you could do one of two things:
(1) Check Ann's chest area for a clue to her cause of death. For example, a sim who died by pufferfish poisoning might have one swimming around in their body.
Or a vampire who died by sunlight might show a small sun in their chest. (I'm not sure but I think some ghosts indicate their cause of death by behavior instead of an object in their transparent chest.)
(2) You could also save your game and befriend Ann so that she joins your household as a ghost.
(I only suggest saving your game first in case you're just curious about Ann but don't want her permanently rejoining your sims' household. Once you satisfy your curiousity, you can exit without saving.)
Once Ann's a household member, you can check her Simology panel which will describe her cause of death.
I'm not sure if this will be helpful. Good luck!