Is a child obliged to pay off his parent’s debt?
Question

My mom do not pray. From what i know, she is considered a kafir. Since i was young, she has the habit of borrowing money and not returning. She will promise to return when borrowing but will not do so. She does not take her fasting or prayers at all. Since this is the case, am i suppose to return her debts if she happans to die? From young i have been telling her the importance of islam and to return the money. But, she does not listen. From what i know the amount is too much to be paid back also as it riba was involved. She will rather go on holiday then pay back the money! The people she borrowed from are mostly kafirs also. I do not think i can afford it at all. Please tell me what to do. Alhamdulillah, under the help of Allah, i have been guided. My mom does not pray, pay zakat, does not fast, or does she wears the proper hijab. Please reply.
Praise be to Allah.Firstly: 
You should give thanks to Allah for blessing you with guidance. This is a blessing which many miss out on, and you can see that the closest of people to you is missing out on it. Giving thanks increases the blessing, as Allah says (interpretation of the meaning): 
“If you give thanks (by accepting Faith and worshipping none but Allah), I will give you more (of My Blessings)”
[Ibraaheem 14:7]
You should do your utmost to save your mother from the Fire, by calling her in the way that is best to the path that is straight. Always remind her of the Hereafter and the meeting with Allah, exhort her and warn her, that Allah may set her affairs straight. You should strive to do that without feeling despair or giving up. Look for people who can influence her heart and mind among her siblings, friends and neighbours. May Allah guide them to the straight path.  
Secondly: 
You are not obliged to pay off her debts – even if she is Muslim – either during her lifetime or after she dies, unless she has left money behind, in which case you must pay off her debts from her money (the estate) because that has to do with people’s rights to the money. If there is enough money to pay off the debts, all well and good, otherwise none of them has the right to ask you to pay off the debt, because the debt was owed by your mother, not by you, and you have nothing to do with it. But if she dies as a Muslim, then it is recommended for you to pay off her debts as a way of honouring her, but it is not obligatory. 
Shaykh al-Islam Ibn Taymiyah said: 
The heirs are not obliged to pay off the debts of the deceased, rather it should be paid from his estate. 
Minhaaj al-Sunnah, 5/232 
You should warn people against giving her money, because that is a way of offering sincere advice to them and protecting their wealth, and because it will reduce worldly obligations and punishment in the Hereafter for your mother, which would result from her taking people’s money and not returning it. 
And Allah knows best.