User blog comment:B214/High School DxD EX/@comment-219.92.252.80-20160129063342/@comment-76.117.122.127-20160129185618

OK, it seems that her mother is indeed Elmenhilde. This comes from a recent post on AnimeSuki stated in a way that leaves no doubt in my mind despite Ariel not confirming it. And it makes sense to me. Ishibumi recreated the Gemory Group+1 10-person team with Issei's children. They each take up their mothers' roles in the Gremory Group, with Airi and Ex also inheriting Issei's role, and Ex primarily taking Kiba's role as well. To fill the numbers Ravel's and Kuroka's daughters were added. But one role was missing: the vampire of the group, hence Ernestine, and since Valerie was definitely Gasper's woman, the made her mother be Elmenhilde.