My mother has confirmed with cervix carcinoma 3rd stage and she is undergoing chemoradiation treatment, so after tteatment is there any chance of recu?

Good chance to contr: Stage 3 cancer of the cervix is controlled in most patients. So the odds are quite high that your mother will do well in the long term. But there is still some risk of recurrence such that she should remain under surveillance and have check ups as advised by her doctors, at least for 5-10 years. Then she can be more sure that her cervix cancer will not recur.