Jealousy on Nana’s part can be understood, he is her only grandson, whom she raised herself after the death of his family... especially since Nana’s husband(ex), even as we understand, did not pay much attention her... so it seems to me that Nana will also be in the future will want to get full attention from Mc more when she fully knows that he is having fun with her daughters and granddaughters...
Everything is slowly moving towards this, as soon as she finds out everything, I think then Mc will have to arrange everything beautifully for Nana so that she gets what she has always dreamed of and hid