It won’t be easy.
Writing speed is very important in the Malayalam language paper. You should be able to write answers at a fairly good speed and that too without spelling mistakes.
Besides, it is also important to have a good command over the language and aptitude for literature for Malayalam Paper because it requires good imagination to write good language essays. If you are a person who can simply speak and read colloquial Malayalam, be ready to work really hard if you want to take Malayalam as your optional.
The materials of Pala Civil Service Institute would be a good starting point.