Triple Talaq

Sir,My brother married in 2010,the second day girl said i dont want to stay with husband and she went to her maternal place the other city where she was working with her brother and mother.she refused to signed and divorce paper and refused to cohabitat with my brother.So my brother gave triple talaq in presence of the girls brother and other witness.her brother gave in writing that her sisiter was given divorce in his presence.The girl in other city where she was working ,never called my brother,no communication between them.they lived there life sepretly.During this period Girls made Adhar Card on her address the other city where she was living without know my brother and my family. In the year 2012 my brother died.All his property was nomited to his sisiter in 1999.almost 15 years back he never changed his nomination since family don't have any objection on that ,they knew this property belong to my brother and my sister. But after the death of my brother,the women came after one year after the death claiming the property.All knew that she went away even her brother. Now she went to the court for heir certificate.How to prove she is divorce?we have witness