One sided bet

Q: Me and my friend were discussing about marks of a certain exam and my friend said "I won't get more than 20 marks". I said to him "You will get more than 20 marks". He said to me "If I get more than 20 marks I will give you a treat". When results came out he scored more than 20 marks. Is it permissible for me to take a treat from my friend. Is it counted as betting/gambling?

Being concerned about the Deen of a female family member

Q: If a Muslim woman,who is married and having kids, does not offer namaaz and never do other mandatory practices and she doesn't have basic knowledge of Islam, although she is an educated woman and she never shows her interest in Islamic knowledge. So what is the way to let her on the right path. Who will be in charge to let her back to right path or who's responsible?

Maintaining ties with one's mother

Q: I have not seen my mother for 15 years. Now I am 20 years old. There was a problem between my dad and mom as my mother a had a habit of robbing and it was very embarrassing. There was huge fight between dad and mom and So she left the house and went away. All these years I was living without her. But I recently got to know that she is Saudi Arabia. What should I do? Should I tell my dad or not because he hates her and the second thing is should I contact her? I am confused my heart says I should but I don't know what to say.