I have an open source github Library that i need to use for work, however there is no LICENSE file in the repository. The library itself is a derivative work (porting to another language) of a library with MIT license. In this scenario, can I used the library under the terms of MIT license or is it not allowed?
Irrespective of what something was derived from: no license = no license, thus nothing beyond normal copyright law.
One might come to a different conclusion for a derivative of something licensed under a strong copyleft (like GPL) which requires that derivatives grant the same rights as the original wrt distribution of sources and binaries. Yet even then it's legally grey area.
However the same cannot be said and assumed for projects derived from a project with a weak copy-left license like MIT, BSD, Apache, etc.
As such everything which was said in this question and its answer applies.