Why are McNabs a pillbox?

I'm not sure what you mean, but the McNab home is like a tonic to Maniac, who feels like he belongs there.

In Chapter Thirty-Nine, McNab is creating a "pillbox", reinforcing the home to protect the family from the East Ender's revolt and looting. Cinder blocks are used in the living room, bars are place on the windows, and a steel door is created.