What are all those fuzzy looking things out there? Trees? Well, I'm tired of them and rolled her head away.
Well, it looks like the speaker's grandmother didn't even know she was staring at trees the whole time. Her near-blindness and dementia keep her from recognizing what they are. To her, they're just "fuzzy looking things."
The last two lines pay off the poem's title, and we get to hear the grandmother's last words: "Trees? Well, I'm tired of them."
It's almost funny, though in a sad kind of way. The speaker's grandmother gets in one more sassy quip before she goes.
It seems that it's her way of saying she's done with the world. She's seen plenty of trees, and she doesn't need to see any more.
It's up for debate whether she literally dies when she "roll[s] her head away." But what is clear is that, with that final statement, she detaches herself from the world of the living.