Mrs. Jellyby is a philanthropist who is so obsessed with setting up settlements in Africa that she neglects her own home, spouse, and children. Wrapped up in her project, she is callous and heartless even when her daughter pleads for her attention.
Like her daughter Caddy, Mrs. Jellyby is a non-passive women. In fact, she's about as active a character as we've got in this novel. All day long she is writing letters, compiling lists, and dealing with all the paperwork of her project for creating totally unnecessary settlements in a made-up African country. She clearly thinks this charity work is very important, but there is no way to see her as anything other than ridiculous woman, who doesn't care at all about her husband, children, or anything else in her vicinity.
Mrs. Jellyby fits into the novel's discussion of charity, being a kind of walking joke about the way helping those far away can blind people to problems at home. (Or at least this is how Dickens thought about it.) Her children are as wild and neglected as she imagines the African natives to be.
Why bother trying to fix things halfway around the world when right under your nose are Jo and the Neckett children? What do you think – does charity, like the proverb says, begin at home?