Character Analysis
There's Grandma Sweetwine and then there's Grandma Sweetwine's ghost. The former was super close with Jude before she died; the latter haunts her granddaughter (in a friendly way), offering up advice. "She's like my conscience or something," Jude says. "That's what the counselor at school said anyway…." (2.227) Whether or not her ghost is "real" is an open question in the book, even to Jude.
Grandma Sweetwine's in no way your stereotypical old lady. She was superstitious like whoa, and wrote a "bible" that Noah describes as "an enormous leather-bound book stuffed with bats*** ideas (aka: hogwash)." (1.73) Jude inherited it after her death, and takes its lessons very seriously.
One last fun fact: adorably, Grandma Sweetwine "has a great passion for David Bowie." (4.623)
Who doesn't, Grandma. Who doesn't.