Need to way devorce husband and get the my maintainance and alimony

I am writing this behf my sister,nAnd Need an advisory ...She was Married in 2019 nov and after marriage ,after few days they made different house to my sister and husband , starter living seperatly, (even my sister dint asked for separate house), and his mother started to scolding u have separate my son and all, and after few days she came to his son house and started telling my sister she will make his son remarry and u are not good and started murmuring about my parents and all drama happened, and she called me and told me to take her into her parents house and I went and told both of them husband's and his mother to bring mediator (the one who fixed Marriage) and told need an discussion, and took her to my home, it is almost 2 years now, they have not contacted us, we tried initially to contact his releatives neither worked, recently I called his husband asked to give her belongings and he returned and my sister want devorce now,. As she don't have any left over trust , pls help