Dejar used with objects
To say "Her mother wouldn't let her leave", would you say "Su madre no la deja salir" or "Su madre no le deja salir".?
2 Answers
It appears that your question concerns whether the person being denied permission acts as the direct object (la) or the indirect object (le) of the sentence. In this case, "le" would be the correct choice.
The syntactic structure can be analyzed by considering first what is not being allowed. Here we see that "leaving" is what is being disallowed, making it our direct object. This leaves the affected party as our indirect object, or in this instance, it indicates the person to whom such permission has not been granted.
In terms of your overall translation, I would suggest that you reconsider your verb tense as your sentence might better be translated (depending on context) as "Su madre no le dejaba salir."
no le daba permiso salir
no le dejaba salir
