Question Summary:
My husband is studying full time and not working so I support my family. My mother in law has no money and is very sickly and needs somone to pay her medical bills….Islamically is it my duty to support her financially?

Question Detail:

My husband is studying full time and not working so I support my family. My mother in law has no money and is very sickly and needs somone to pay her medical bills. Can I make the intention of sadaqah or lillah for the money i contribute to her bills? She also has other working children but they do not contribute to her upkeep and bills, Islamically is it my duty to support her financially?

Answer :

In the name of Allah, Most Gracious, Most Merciful
Assalaamu `alaykum waRahmatullahi Wabarakatuh
We acknowledge the services and khidmat you are providing your mother-in-law with. Surely, your efforts will not go unnoticed in the court of Allah Ta’ala. May Allah Ta’ala reward you abundantly and make this a means of your success in this world and the hereafter, Ameen.
1. Yes, it is permissible to make intention of sadaqah and lillah for the money you contribute in purchasing pills for your mother-in-law. 
2. Islamically, it is the responsibility of your father-in-law to support your mother-in-law. If your father-in-law has passed away, it is the responsibility of her children to support her. Islamically, it is not your responsibility to support your mother-in-law; however, morally it is encouraged to support her, as you are presently doing.
 
والأم إذا كانت فقيرة فإنه يلزم الابن نفقتها وإن كان معسرا ( الفتاوي الهندية 1/565,رشيدية)
ومراد المصنف من إيجاب نفقة الأم على الولد إذا لم تكن متزوجة لأنها على الزوج كبنته المراهقة إذا زوجها صارت نفقتها على زوجها ( البحر الرائق 4/207, رشيدية)
And Allah knows best
Wassalam
Ml. Talha Desai,
Student Darul Iftaa
Checked and Approved by:
Mufti Ebrahim Desai
Darul Iftaa, Madrassah In'aamiyyah