？
Did she go to the concert last Sunday?
Literal
She [topic-は] this-time-before [genitive-の] Sunday [on-に] concert [to-へ] went [question-の]?
The sentence-final の (without か) marks a casual question — softer and more inviting than the polite ~ましたか or even the colloquial ~ましたか. Common in conversation between friends or family. この前の日曜日 ('last Sunday') is the standard way to specify 'the most recent Sunday' — この前 attached genitively (の) to the day. The directional へ on コンサート frames the concert as a destination. The question opens space for the listener to respond rather than demanding an answer; written with a question mark to mark intonation, since the の alone could be a mild assertion in some contexts.