Convert EMBP to EPUB

It is not possible to convert Mobipocket EMBP files to EPUB format, because EMBP is not an ebook file. It is just auxiliary file that contain supporting data for the actual ebook, so embp to epub conversion is extremely unlikely. In case that you want to convert the ebook you have to look for the PRC file.

Simply put, it is impossible to convert EMBP to EPUB directly.
Thus, there is no so-called embp to epub converter or a free online .embp to .epub converter to be found.