You have received an existing open source software component, licensed under the MPL
Your program, including the modified or un-modified component, can be licensed by you as a "binary executable" under any licence of your choice (for example, the EUPL). You may even select a non-open source licence (a proprietary licence).
How to select a licence for your program?
This is applicable to the object code of your program "as a whole", including the binaries generated from the received component.
However, the source code of the received component stays under the MPL and, if distributed, must be propagated under the MPL. Therefore you need to the document the two licences in your files: the licence that is applicable to your program and the MPL licence that stay applicable to the source code of the received component.