Brigades did not have color guards - there is nothing in the cavalry drill manuals used in the Civil War that allowed for such. The color guard specified for a regiment was the color bearer and one guard (unlike the Infantry CG which was one bearer and 8 guards for CS units and two bearers and 7 guards for US regiments) and this was for both sides.

That Alabama company was probably, at least for a time, Rucker's escort company.

Greg Biggs