does Wal-mart have a policy about employing Muslims?

I'm sure they do but we don't have very many Muslims where I live so I haven't seen one. Wal-Mart, being the largest retailer in the world also has the biggest bullseye on them so they wouldn't do something stupid that would allow an easy and expensive lawsuit against them.

Except in very limited jobs (like meat cutters) wal-mart wouldn't have a legitimate, nondiscriminatory reason to prevent Muslim women from wearing Hijab at work.

I live in an area where there are many more Muslim women, but few Wal-Marts. Many are employed at Target, and many wear Hijab (although red colored with khaki skirts, to fit into the team uniform...)

I think they claim to be an equal opportunity employer.