I think that the location in Cambridge is probably very safe. That area has the same issue with homeless population that many cities have, but not anything that I would be concerned about personally. Also, the streets are pretty busy with students, so I think it's rare you will be walking down dark streets all alone if you know what I mean.

It is also, in general, a nice area with cafes, interesting restaurants, etc. Personally, I would prefer it to something that was more downtown.

If you're looking for the "safest" place to live, I would look into Brookline