Young readers fantasy book name. HELP!!?

I read this book about a girl with neglectful parents....she lives in a small town....She also has an older sister who takes care of her. In the beginning of the book she gets a ride on a carriage to the nearby city. She goes into a town meeting and finds out that the town is overrun with rats. The mayor wants to hire an exterminator who uses wolves to kill the rats. A woman ejects saying something about what happened last time. Thats all i got up to in the book. I also know her mom gives birth to a girl they name anything (i think) then her parents die (or leave her... im not sure) i think the book might be called into the woods