1) your grand mother can make application to senior citizen maintenance tribunal and seek maintenance from hr sons
2) in the alliterative grand mother can make application under section 125 Cr Pc and seek maintenance from her sons
3) An application for maintenance may be made
by a senior citizen or a parent, as the case may be; or
if he is incapable, by any other person or organization authorized by him; or
the Tribunal may take cognizance suo motu.