If she owns old heritage buildings she has a responsibility to maintain &/or restore them. The city let her get away with letting them disintegrate for way too long imho.
When she bought them or inherited them there was no such thing as heritage preservation rules etc. So the city should not be able to throw that tag on them when going in there was no such thing. Now, if someone buys a building now that has similar restrictions on its use etc. then its fair game.