Maintenence

Try to conciliate the matter as you said that wife along with kids are ready to wanted to return back.

 If conciliation fails file a case of 125 crpc1973 maintenance and if husband fails to give maintenance then he go to jail. You said that Husband is handling all business but legally it was in elder brother's name and hence all business belongs to elder son.  So, don’t worry hire a good advocate and file 125 case and I am sure that he should give maintenance as nobody wants to go to jail .First step to conciliate the matter if husband disagree to take her back then file a case for 125 crpc,1973.

yes she can 

Dear Mohit,

What is the reason he deserted her, do u know what is his intention?  As per your version he does not own any properties on his name and even he dint have any income officially.

As Khushan vyas sir said, first try to reconcile the matter with elderly people.  Even then if the things does not work out, what i feel you just file Restitution of Conjugal rights.   what is wife's profession? is she working or house wife?  Later, based on the reply from husband you can take further action whether to file crpc 125.  Becoz, saving the marriage is first preference, rather than just aiming at maintenance (anyway you have that option later).  So think in those terms.
 

Will against younger son. Seems that his wife is a diehard obnoxious woman who seems to have annoyed her in laws so much that the will is in favor of the elder. In view of your in forma status court can't force o you to give her any maintainence. If lower court acts against common sense or whatever, move the High Court and if you don't get justice there appeal in the Supreme Court.

1. She is a house wife.

2. Tried many times with elder people but he is not ready to accept her as he doesnot like her wife from day 1

3. His allegations are she doesnot care for him,She doesnt know how to tackle husband.

 However wife alleges he used to drink every day and abuse her parents and a chain smoker and also doesnot care for her and his child. Whene ever he gets time in night he used to love his elder brother's son. When asked about this he said my elder brother and his wife is god for him as his father has expired so he took care for him so he wants to give everything to his family. He didnt want his own family.

She doesnot want to go to police station and court for this .

4. His elder brother and wife used tried to create differences always from 1st month of marriage between her and him. He said he only believes them not any other person inthis world.

5. Wife doesnot own anything neither her own belongings/ Jewellery nor any property. Her parents asked for it then they said we wont give until you take divorce and doesnot give any alimony .If you can prove in court then take it.