Property claim

No she cannot claim share in her mother in law's property.

Rgds,

Nitin

It depends on how she acquired the property and several other circumstances like father in law earnings kept in the name of undivided member, etc.,  If she is having independent source of income and acquired the property with her source without from any other member of joint family , she is having liberty to bequeath the property to any one as per her will.  Whether mother in law is still living or left a will etc., are required.

Details inadequate.