Noelle doesn't even know she also avenged her mother.
She has to get rid of Megicula to avenge her mother as it was Megi who killed Acier not Vanica. We saw last chapter that Acier dealt a lethal blow to Vanica that Megi had to use a devil language curse on Acier and then had Vanica flee.
Noelle doesn't even know she also avenged her mother.