Vagus nerve stimulator

I would like to know which method to should I use correct the artefact cause by the vagus nerve stimulator on the MEG

thanks in advance

You could try SSP or ICA:

Colleagues who have been working with spinal cord stimulation just told me that if the stimulation has a very specific frequency, a simple notch filter may be sufficient.
Otherwise a band-pass filter to keep only the frequencies of interest in your study.

Additional suggestion from another colleague:
For the SSP computation, try to narrow the frequency band, and use long segments or entire recordings.