@ Author
Try to understand below
1. Hire a Family law Adv. or the young boy and show him this reply..
2. A un-employed person can marry and there is no Law of the land which says that he cannot. marry Some time pass female writers comment here saying that how a un-employed man can marry?, ignore such stupid time pass comments of these time pass female writers having no legal knowledge. Further, a un-employed husband living in the home of his parents can very well upkeep his wife from joint income from a joint family kitty. S. 125 CrPC when is filed by wife it is for for seeking maint. from husband and it is not for seeking maint. from in-laws (father in law running a grocery shop is nothing as evidence for maintenance in case in hand). However if Husband is dead then wife under S. 125 CcrPC is eligible to seek maintenance from In Laws on compassionate grounds which is not the case in hand. Further, there are no maintenance Law of the land which says that only from husband's earning a wife needs to be maintained.
3. Now the moment this situation takes a flip as in your brief the first thing the boy should do is to enroll into some kind of regular studies and posses a valid Student ID Card.
Reasoning: A student husband under S. 125 CrPC need not have to pay maint. to his wife as he is not earning a income to maintain status. S. 125 CrPC law does not say that boy's father or parents income will be considered now to meet maintenance to boy's wife. There are catena of Judgment which says what I am saying so in such situation either the wife will opt for Divorce or will re-consider her decision to resume cohabitation in boy's home and she can't now refuse and if she refuses then she has to give valid reason for such refusal.
4. Hence there is no legal liability of father of boy to pay maintenance out of income from his grocery shop to Daughter in Law it is responsibility of his son who is husband to this wife but if husband is un-employed then he is considered able bodied person and comes under minimum wage act considered minimum wage earning adult which national average is to be Rs. 4,500/- but the moment the boy legally is shown to be a student even this able bodied persuasive inference goes for a six and hence wife is denied maintenance.