mother visit visa sponser self employed

[SSWSZ]

hi.
my mother in law got refused for visit visa and here i attach the letter .my hubby fully sponser her .both his parents are above 65 of age and no income of their own whatsoever .no property no job except the house they are living in.
they have 5 daughter all married and setteled in same city with their respected families.
can any one plz give some idea what king of documents will be helpfull if we apply again .attached refusal letter .
and also this is the second time her visa got refused first refusal was in 2009 and now in 2015 .she also got refused for cana visit visa and its declared in both application
thanks alot