I am truly sorry for you and your mother.
That would have seemed a never-ending nightmare.
It wasn’t about the book. The commie occupation forces did have a list of books to destroy and they did that when they found them in libraries, but they didn’t hunt them.
The mechanism was to have a system where everyone is guilty of something and can be jailed at any time.
Their problem with Dr. Roose was that he hosted discussion evenings at his home. That is why they did a search in his home and by finding this book they now had a reason to imprison him.
My grandmother had books from before occupation, but since she kept quiet they didn’t care.