What was the name of hazrat Mohammad saw great grandfather?

he was hindu and his mother was also hindu and they both were follower of lord shiva and actually under that black cloth in mecca is big shivling and muslims are afarid of showing that to rest of world if it will be shown then they have to accept that they are origenated from hindu . as everyone know that the oldest book is reg veda . if they are not afarid then please tell them to remove the cloth so that people can see the truth