Share 'muslin'

I'm wanting to get some ideas on good muslin to purchase that also lends itself to hand quilting.  A friend has asked me to assemble a quilt top using some butterfly blocks her aunt made probably in the 1940's.  These are all attached to a muslin base with various embroidery stitches.  I want to also surprise her & hand quilt the top before I give it back to her so any suggestions as to the b…