Maintainance

there is no provision under 125 Crpc about to Mother-in law, but if the dauther in law have the property of her husband then she can be file a civil suit for maintinance

the property of the son devolved upon the son's wife the son's mother can claim by way of maintenance.

If mother and wife are the only legal heirs, then both of them can get 1/2 share each and mother can get maintenance out of that property.