She died and left behind a mother, two sisters and a husband
Question

                A woman died and left behind a mother, two sisters and a husband. How should the estate be divided?.
Praise be to Allah.
    The mother gets one-sixth, because of the presence of the two 
    sisters. Allaah says (interpretation of the meaning):

    “if the deceased left brothers or (sisters), the mother 
    has a sixth”

    [al-Nisa’ 4:11]. 

    The two sisters get two-thirds, because of the words of 
    Allaah (interpretation of the meaning): 

    “If there are two sisters, they shall have two-thirds of 
    the inheritance”

    [al-Nisa’ 4:176]. 

    You, the husband, get half, because Allaah says 
    (interpretation of the meaning):

    “In that which your 
    wives leave, your share is a half if they have no child”

    [al-Nisa’ 4:12]. 

    The sum of all these shares is greater than the estate, and 
    the scholars call such cases al-‘awl, i.e., the sum of allotted 
    shares is greater than the estate. So the share of each of the heirs is 
    reduced in line with this excess, which in this case is one-quarter. 

    In that case the estate should be divided as follows: it 
    should be divided into eight equal parts. The mother gets one part, the 
    sisters get four parts and the husband gets three. 

    Each heir is given his or her share as follows: 

    The mother’s share = the estate x 1 / 8  

    Each sister’s share = the estate x 2 / 8 

    The husband’s share = the estate x 3 / 8 

    And Allaah knows best.