Mother's property

My mother has 4 children 2 brother's and 2 sisters .My father expired when my elder brother was 5 yrs,myself 3yrs, younger sis 1½yrs and younger brother in mother's womb 8months old. At present in which house we are staying my father had taken on 11 month agreement on rent, unfortunately my father expired within 6 months. My mother took a lot of trouble and struggled hard to take this house and bringing up 4 children.Now we are all married when my elder brother got married in 2000 very soon after 2 yrs there was a dispute quarrel and fighting with my mother and sis in law.she started demanding for share,as I was staying with my husband on a rent house . My younger sister who is a Hitler she made the power of attorney on her name as she was also married and staying in Goa. My mother did this because it was her hard working purchased house,she did wanted to go in wrng person hand so my mother brought me in that same house my birth place as I used staying in rent house with my 1 yr old daughter . My mother expired in 2011 on 29 August . When my mother was sick no 3 children came to her help I was only 1 who took care of my mom and also my mother didn't want to die. As due to heavy rain in 2011 on 27-28 August I could not admit my mother so my mother requested me to bring an advocate she pleaded but I didn't listen to her only I said Mumma you get well soon & den I will get the adv. In front of u . On 29 August as I was taking to hospital on the way she expired ,she got an attack. Now where we are staying the apartment of 1bhk of 340 is going to start in the month of December . My sis came running all the way from Goa to this house . Now she is telling me to go out of this house as this house belongs to her. What should I do????