I have been looking in registration thread about Italian silverware and jewelry maker and couldn't find this identification:
750 is obvious but the 3 VI i know VI is for Vicenza but i can't find any register number for 3 VI
there is also this last hallmark i cant identify look like its labeled FOB but i might be wrong
this is on a watches my GF Nona's had when we moved to Canada
Picture:

Sorry for the finger in the picture only way i could old the 10x in front of my phone
i can take more picture if needed