I am partial to Lab's. they are a bigger dog, and eat plenty but they are very smart, don't need grooming (tho they do shed) they are the sweetest dogs. Will she be able to walk with the dog a lot?
I have a young friend that is OCD and nervous, she has a little chihuaua dog that helps keep her calm, though the dog is not trained as a service dog, she functions better when she has the dog with her.