Well, what are you watching...??
And I mean, you said you were doing something, so she has a reason to "blame" you... I mean, if I stole something, and someone blamed me, uh, yeah!! They have every right to!!
I would kindly have a discussion with your grandma about why she thinks these other shows are bad.
Just keep in mind she won't be here one day. She prob doesn't have all that much time left. Just try and make her happy while you can, even if that means watching shows when she's gone out.
Best of luck!!