i’m pretty sure Belle’s mom is truly dead. OUAT at the end of the day is part of the Disney product line and while they have leeway on playing with fairytale characters’ plot lines they do not deviate from what is Disney cannon. In Beauty & the Beast, Maurice is a widower. In the original B&B tales, he is also a widower. Changing that probably isn’t going to happen. I think the point of the plot line point was Belle could have eventually found out the truth without having to have ventured to see the Rock Trolls, and her memory loss was simply PTSD. The flashback tie in was that it brought about how Rumple was called into play by Maurice in the Ogre Wars