Worcester Police maintains a website with crime statistics of specific areas of the city. (link attached). That might be a good place to start. Another interesting website is FamilyWatchdog.com which shows sex offenders who live or work in any area.
You should visit your niece & explore our city!
Jeff, let me know the specifics on where she is moving (or if she needs any assistance in the area) and I will be able to help. Webster Square isn't necessarily the best part of Worcester but it isn't too bad either. There are differences based on exact location in that area so just let me know the street or address and I could let you know what I think.