mongodb not starting giving me error non start

hello to all i am trying to setup an mta basically node js and mongodb based its name is zonemta but dont know why mongodb dose not start always stuck on the error tried to search solution but did not found here is error logs which i get

ERR! Queue Could not initialize MongoDB: connect ECONNREFUSED 127.0.0.1:6379
npm ERR! code ELIFECYCLE
npm ERR! errno 1
npm ERR! zone-mta-template@1.5.0 start: `node index.js --config=config/zonemta.toml`
npm ERR! Exit status 1
npm ERR!
npm ERR! Failed at the zone-mta-template@1.5.0 start script.
npm ERR! This is probably not a problem with npm. There is likely additional logging output above.

npm ERR! A complete log of this run can be found in:
npm ERR!     /root/.npm/_logs/2018-12-04T13_41_09_429Z-debug.log