"Where does she go at night?"
Translation:वह रात को कहाँ जाती है?
It corresponds to the 'at' in the English sentence. को is often omitted for सुबह (morning) but is necessary for other times of the day.
Got incorrect when I entered the same words in a different sequence with " raat ko" रात-को at the end
Voh kahã jata hé raat ko? ... any native or near native speakers want to tell me that's totally wrong, or sometimes allowed?
Hindi uses subject-object-verb sentence order. So, the verb phrase 'जाती है' must come at the end.
This is similar to the declarative sentence 'वह रात को वहां जाती है' (She goes there at night), where changing the sentence to 'वह वहां जाती है रात को' is incorrect.