According to
this, there is a thing called
NnpcRoomMarkerFtrFloor2x1 in Blanche's house, which is a red wireframe box where nothing is there. If you look at
this, which is Marshal's interior, you'll see something called
NnpcRoomMarkerFtrFloor1x1, which is also a wireframe. Sometime ago, I guess one of the villagers gave Marshal an umbrella. So now
NnpcRoomMarkerFtrFloor1x1 is occupied with an umbrella, which is a 1x1 item. If you give a stereo to Blanche, it might occupy
NnpcRoomMarkerFtrFloor2x1, which is the bottom right location when you walk inside her house. A stereo is a 2x1 item. If you plan on doing this, then it may take that unused spot. I can't find anything about Blanche with a radio online, so this may be a risk you'll have to take unless someone else has given her a stereo and can confirm what I mentioned.