
So, Granny Orne (0) is a decent L0 ally for Agnes. She comes with a +1 boost, unlike Peter Sylvestre (0), and while she can't soak horror quite as well as Peter, she still gives you a decent buffer on Agnes' precious sanity. Especially significant if you're working from a limited card pool.
I think it's also worth considering that Granny (0) is very helpful for allowing you to trigger Grimm's Fairy Tales, which is actually a pretty efficient horror healing card if you can get it to fire reliably. If you fail a test you are normally failing by 1 (which Granny can make 2), or you're failing by 2 or more.
I think there's a really interesting Agnes deck here that takes a bunch of failure cards. Both "Look what I found!" (2) and Dumb Luck (2) are pretty great cards in their own right. There's also stuff like Live and Learn, and Old Keyring, and you might not even mind running Rabbit's Foot if you're getting the already from Granny.