Does his mother have any interest at all
in going either? I agree with you, I think
baseball is dead boring if you have to sit through the whole thing in a stadium.
Maybe there's something that all three of you actually want to do - maybe a Comedy Shop show or a movie and dinner, some kind of live theater, something else besides baseball. Unless, of course, if she is REALLY a big baseball fan I might go just to be supportive of her and make it fun for everyone.