The plot sometimes introduces characters then they go back into the past like, 4 days earlier, then they won't even mention when we are into the present day again, you just have to assume, also the main character is just slaughtering monsters, he just gave up on his mother being alive, I guess its okay since hes a thirsty monster. However why not use his authority to look for her, it isn't hard for him to find out by maybe getting someone to backtrack to where she was at the time of the incident. I know she told him not to kill people and now he assumes shes dead with little doubt, so hes gonna go on a rampage, however he keeps saying he will take revenge on the people who made this game, either for his dead mother or to protect her. Then makes no effort to confirm if shes dead or alive. I mean he knows himself people are being killed I mean hes told minjin that the food supplies will have a massive shortage every 10 days, so shes slaughtering anyone who doesn't fight, wouldn't that mean if his mom doesn't fight she will die, since minjin wouldn't know her? If his mom survives all of the sh*t thats been going on then she has some thick plot armor, since monsters legit kill the weak easily, the only ones surviving are those who can fight or those (Yoon Girim) that can honey d*ck someone to save them.