。
May my daughter go to school?
Literal
Daughter [object-を] school [to-に] cause-to-go [even-if-ても] good [polite-です] [question-か].
行かせる is the causative of 行く ('to let/make go'). Combined with ~てもいい, it's 'may I let [my daughter] go?' — a permission question about letting a third party do something. Common parenting phrasing.