What stabilizer should I use for redwork embroidery on flour sack dish towels?

as sewhobby as suggested WSS - WSS is what I like to use for that, too.

Here is a stabilizer guide you can chk out. I would use the tear-a-way.
http://www.emblibrary.com/EL/elpr...

You can also use the same thread in the bobbin as you do on top if you want. Here are some tutorials you can look through for other projects you might want to do.

http://www.emblibrary.com/EL/Proj...

I'd use a water soluble stabilizer so it will be gone after laundering.