In reply to pawan:
You still provide too little information, as usual. We don’t understand the timing of your C based code in relation to your class based testbench. Are you using only functions to import/export to DPI or tasks?
You can certainly have class based methods get called from C by using wrappers (Same as you would between C and C++). You can export a non-class task/function that has a handle to the class method either stored statically, or looks it up. Then when called, it calls the class method using the handle as a reference.