Several reasons it could be in MO. Mom and Jessica once lived in MO, so orginial case was in MO. Dad filed in MO, and mom didn't contest jurisdiction there or dad had filed before mom and child met residency in CO. Normally the case is heard in whatever state the child has residency in at the time the case is open. That state will remain the state that has jurisdiction even if a party moves out. If both parties move out one can file to change jurisdiction. If mom and child moved from MO, MO had the orginial case, dad still lives in MO, the courts usually won't change jurisdiction as one party still lives in MO.
Mom could have an attorney in MO who went to the hearing in her place. Most often though if they do this, they have the party do a phone in for the hearing. It would be not to smart in my opinion to not go to the hearing or try and do a phone in, even with a lawyer there to represent you.
I don't know MO family law specific, but I do know other states and generally things are done along the same lines.