A very good point available in this judgment from the JMFC. Ongole, for those who are facing Domestic Violence case as well as IPC 498A wherein the allegations are same in both.

When the husband of a knife dies, maintenance of the daughter-in-law falls are the parents-in-law as long as she is alive. There is no  requirement of law that a grandfather is under an obligation to maintain his grand child when the mother of said child is alive.

Index of PWDV Act cases here.