Baby Shower Etiquette?

I need some insight on how best to host a baby shower for the mother-to-be of my son's child. They are no longer in a relationship, but remain committed to raising my grandson. Because the girl doesn't have a good relationship with her mom, who lives across the country, I volunteered to host a baby shower in her honor. In the invitations, what do I refer to myself as, the 'paternal grandmother of the baby'? 'Kase(the baby's name)'s GeeGee(what my other grandkids call me? My son expects me to invite his current girlfriend, because he says the two women have met and are 'friends'. Because I don't live in the same city as they do, should I have the shower at the mom-to-be's place? HELP