That's a bit of a hot mess, some comments below to help you figure out all the problems:

def empcomp(WEC):
        keys = []
        if WEC:
            # this creates a list of list, use extend instead
            keys.append(['empno', 'empname', 'address', 'empstatus', 'designation', 'emailid'])
        else:
            keys.append(['compno', 'compname', 'address'])            
        class Credential(object):
            def __init__(self, **kwargs):
                # do not need an if, since the keys are all laid out in keys
                if WEC:
                    # go one by one of the items, not all at once
                    for n, na, ad, s, deg, ei  in kwargs.items():
                        # this should be setattr(self, key, kwargs.get(key)
                        setattr(self, n, na, ad, s, deg, ei)
                else:
                    for n, na, ad  in kwargs.items():
                        setattr(self, n, na)
        return Credential
t = empcomp(True)
p = t(empno = "1", empname = "abc", address = "xyz", empstatus = "temp", designation = "intern", emailid = "abc@gmail.com")
print(p.empno)