A quick Google search for "anime nemesis wizard witch" points to Radiant, a French comic series adapted as a two-season Anime.
Wikipedia plot summary:
In the world of Pompo Hills, an race of monsters called Nemeses fall from the sky. These creatures contaminate everything they touch. People who survive their contact become cursed, but also gain the ability to wield the magic power known as "Fantasia", thus becoming Sorcerers. Seth, the protagonist of Radiant, is a 15-years old boy who has survived a Nemesis attack. He dreams of defeating all of the Nemeses and bringing peace between Sorcerers and the rest of humanity. To do so, he has to find the place where the Nemeses come from, the legendary Radiant, and destroy it. He and other sorcerers travel the region in search of Radiant whilst avoiding the Inquisition, an organization opposed to the Sorcerers.
Alma (アルマ, Aruma) - A woman who is an experienced Sorcerer and Nemesis Hunter. She survived the same Nemesis attack Seth survived from ten years ago, losing her right arm. She since raised Seth and teaches him on controlling his Sorcerer powers.
The blonde girl:
Mélie (メリ, Meri) -A girl with a split personality, she later becomes friends with Seth.