Currently, you can see David who finally woke up from his sleep went outside of the hotel room to eat something. Well, he decided not to go back home and decided to stay in the inner area. Well, he will be staying there for 3 days to a maximum of 5 days and after that, he will go back to the Dungeon.
Also, he already informed his grandmother that he already came out of the dungeon and that it was a wonderful experience for him to be able to fight those peak Mortal-grade monsters.
Even before getting the meta Guardian technique, you can say his grandma gets to know he has the power to fight those intermediate Mortal grade monsters. So when he told her grandma that he fights peak Mortal Grade monsters, his grandma did not say anything to him.