Okay some editing , no , that's not a fanart. Since BONES is starting to branch off from manga as well , maybe they make shinigami is like that. But it's definitely not Maka's mom. Or at least , in the manga it says so because she hasn't appeared yet. Neither it is Shinigami in the manga. I suspect it is an OC because the artwork seems different (hard to say but , that woman's face is abit off if you compare it with Maka's face and Tsubaki's) or maybe it's just a cross-over art , like Eureka
no , I haven't seen that woman in anime yet. If that's true a Maka's mom , it'll ruin everything , including my hope of BONES animating clown arc and such. Though the artwork seems to tick me off a bit.. I don't like her face -_-"