Can the bailliffs take my possessions for somebody elses debt?

(for my mother-in-law) my neice has a debt of �320 owing for a fine she received in 2007. The bailiffs have turned up at my mother-in-laws house demanding payment, as this was the address my neice gave. My mother-in-law is scared witless, and has been trying to get the money together as she is crying and terrified they can take HER stuff. Can they do this? he's threatening to get the police and a locksmith, and kick the door in if they don't pay up by 2:30pm