Is my mum at fault?And will my grandmum's dua be accepted?

My grandmum has a soft corner for my eldest Aunt which everyone know. She would cover her mistakes, praise her all the time and ...... My aunt has taken the authority of building my granddads land (apt) and give everyone their share this has been going on for the past 6 years(ever since he died) yet the apt are not transferred in their names.And she keeps giving excuses all te time for the delay. Yesterday my grandmum called my mum and in her conversation she asked when the apartments will be handed over to everyone and my grandmum got real up set saying everyone should do their own work no body is free to do others work, what my aunt is doing no one would do and ....... so my mum got a bit upset and was a bit harsh in her words but she felt real bad and kept on crying saying she's been a bad daughter and couldn't do much for her family. At this point if my grandmum by mistake brings out a bad dua on my mum will it be accepted???

I mean if parents are at wrong,will their duas be accepted against their children??? Or does Allah only listen when parents are at right???