After death of my sister due to carless treatment of her abortion her husband wants daughter custody

all those allegations of immorality need to be proved in court while seeking custody of child. It apears the marraige is still intact so the mother and father are custodains of child. your BIL cannot force your sister to leave child somewhere else. She can file FIR for harrasment. If they are deivorced then your sister need to file for custody of child and maitenance

Hey Thanks for your revert,

I have mentioned that due to careless treatment of my sister she is no more. And her husband is drug addicted and he want baby girl to stay with him and his family. But he stays in abroad and don't wanna work in India, then on whose responsibility he is trying to take custody as he is self not present to take care of BabyGirl 

Under Section 6 of the Hindu Minority and Guardianship Act, 1956, Mother and father are only natural guradians,; since the mother of child is not alive her father is her natural guardain and it is very hard to prove that he will care for her welfare. STill you can file petition for guardainship but chances are rare

It seens to be that you are muslims so Islamic  law applies for you ,complaint to kazi or Mulla and try to take her to your custody peacefully ,if he behave rudely then file suit under guardin and wards act to take custody of your sister child  by proving in court that they are unfit to rise the child.

The queriest has not cleared which community they are.

Yes, any suggestion depends upon the community as well the personal law, as applicable.

The abov einformation is relevant for me to form a view.