Light Novel Volume 14 Chapter 4 & Anime Episode 10 Spoilers: It is revealed that Elaina's Mother is Victorica (ヴィクトリカ) aka Fran no Shishou (フランの師匠), Fran and Sheila's teacher.

Her appearance is heavily similar to Elaina. She wears a witch hat with a pink ribbon tied around it, a black jacket with pink collars and interior over a red vest. Furthermore, she wears long black socks and boots.

Sometime before the main story begins, she trained Fran to become a witch.

(Source: Majo-no-tabitabi Wiki)

She also uses the pen name Niké when writing her stories.