I've added a --stem <word> option to varnamc. It can only do one simple stemming right now : ാ to ്.
for example:
address@hidden ~/Development/libvarnam/examples $ varnamc -s ml -m പരീക്ഷയാ
Using /usr/local/lib/libvarnam.so
പരീക്ഷയ്
This is because I haven't added the code to check for more complex ending if the first ending is not in the stemrules table in ml.vst