Cruel Behavior of the husband and in-laws and pronouncement of talaq

One of my neighbours was married under Muslim law in 2015, her husband and in-laws have been cruel to her since the beginning. She came to her maternal home once and then they have refused to let her in and have stated if and all she wants to be with her husband she needs to live as they want and should obey them in every sense. Recently she received her first talaq through a letter. There was some mediation going on through a registered NGO but it failed. My question is, does this talaq valid as she is not cohabitating with her husband during the iddat period as mandated by the Muslim Law? What should be her way out as she primarily does not want a divorce and is open for mediation and compromise as she is having a child? What are the remedies available to her to seek her right? Who are the authorities she should approach to resolve the issue? PS- Both the bride and the groom are resident of Delhi only. The groom side is not responding to the call of the bride.