Intent n = new Intent(A.this, C.class);// move from A to C
 n.putExtra("varA", "some value");
 startActivity(n);

Intent n = new Intent(B.this, C.class); // move from B to C
n.putExtra("varB", "some value");
startActivity(n);

Bundle extras = getIntent().getExtras();
if(extras != null)
{

     String aval = extras.getString("varA");
     String bval = extras.getString("varB");
}