If frequency of the incident radiation is lower than the cut-off frequency of the material, what can we say about the photoelectric emission?

The emission will take place only if the intensity is high. The emission will not take place. The emission will take place anyway. nothing can be said.

The emission will not take place.

The intensity only decides the number of photoelectrons and hence the magnitude of the currrent. But for the emission to happen, the incident radiation must have frequency higher than the cut-off frequency.