Yes. it is better to carry with you
temperature in munnar becomes low in november and completly low in december, so it is better to carry woolen with you. It is not neccesery to carry woolen when you are going to Alleppey,the temperature at Alleppey is quite normal.
In Munnar for a night you will feel need of a blanket but just moving out of there it's like Kolkata in other parts of Kerala. Don't overload your bags. Hotels will provide blankets.