Firstly, everything I've found says that Mona and Grandpa should have a joint 8 hour task, but I don't have it, at all. Not even as a blocked job. Does anyone have any idea as to why? Was the task ...
Some players have an issue where the quest line does not trigger, possibly if she was obtained in a mystery box rather than when she was originally released. https://forums.ea.com/en/the-simpsons-tapped-out/discussion/204247/mona-simpson#latest