Ruth Finkle is the grandmother of Allie, Mark and Kevin. Also the mother of Tom and Uncle Jay.
Ruth is mostly always upset about something like when Allie orders a burger at Red Lobster, she thinks its ridiculous since the restaurant is mostly associated with fish but on account of Allie not liking fish.
She also gets mad at Liz and Tom for sending an oven she ordered for them away since Liz and Tom already ordered an oven but it just hasn't arrived yet.
Although she is picky about things, she is also very supportive and even volunteered to buy Allie a present for doing good at the spelling bee competition and babysit Allie's premature kitten Mewsette.