Regarding Final Project for Exam

Can I submit a project with some modification of my own on the project which is already been done by someone else?

You can choose to create a project which has already been created by someone else, but please DO NOT plagiarize the content. Plagiarization will fetch you ZERO marks. You will need to create the project content yourself. So yes you can do that.
You can create ANY project you want as long as it utilizes the Bolt module. Projects which do not make use of the Bolt module will not be awarded any marks. You can use any other board along with the Bolt module for your project, e.g. Bolt + Arduino, Bolt + Raspberry Pi etc.