Sorry for your loss, but I agree with some people here that you should keep the game. You may not play the game now, but keep it as a memory of her and you and the way she fostered your hobby for gaming.
I'm thinking the future you would like to recall her some time, that would be the best time to pick up the game and play it in honor of your mom.
If I can't still convince you, I am joining this contest and if I win, you keep it.