best neighborhood for a single soon to be mom in early 30s?

Look at Chestnut Hill. That area has parks, greenery, yards, etc, and has a great commercial corridor in Germantown Avenue, plus its close to mass transit in the Chestnut Hill East and Chestnut Hill West train lines. Its also very safe and quiet.

It can be expensive though. If its too $ then look at West Mount Airy. This area is directly south of Chestnut Hill. It has all the benefits of Chestnut Hill, but all are slightly less (ie a longer walk to the train, less business on Germantown Ave) but is cheaper.
NOTE: West Mt AIRY and EAST MT Airy are very different, more crime in the east and less space, the boundary between the two is Germantown Ave.