Here's what we know --

A pension appliation was filed in the name of Hiram Taylor asserting that he was enrolled by Capt Ligons and served under Col Underhill. The actual parole for Hiram Taylor, signed at Montgomery AL May 13, 1865, lists him as a member of Co "G", 45th Alabama Cavalry. There was no such organization.

Capt Ligon was Robert Fulwood Ligon, formerly Capt of the "Macon Confederates". This command became Co "F", 12th Alabama Regt. Ligon resigned his commission in April 1862 and came home to serve in the Alabama State Senate. Evidently during the last few months of the war Capt Ligon acted as an enrolling officer for Macon County where Hiram Taylor lived.
http://bioguide.congress.gov/scripts/biodisplay.pl?index=L000306

Col Underhill was Stephen Edward Monaghan Underhill, born in Scotland Nov 6, 1841. He resigned a commission in the British Army to join the Confederate military. In January 1863 he came throught the blockade at Charleston SC. Underhill went to Mississippi and became a volunteer aide on the staff of General Stephen D Lee. On Aug 1, 1864, Lt Underhill was sent to Mobile AL. Shortly afterwards he was assigned to command of newly-organized Alabama Senior Reserves, and the record becomes confusing.

Underhill was appointed Major of William M Stone's 1st Alabama Reserve Battalion. By October 1864 the battalion was increased to a regiment known as the 4th Alabama Reserves, Stone and Underhill becoming Colonel and Lieut. Col respectlvely. Members were supposed to be between the ages of 45 and 50. Stone resigned on Jan 22, 1865, Underhill taking his place as Colonel.
Bruce Allerdice, Confederate Colonels: A Biographical Register, pp 378-79.

Senior Reserves were expected to perform rear-area duties, so both the 3rd and 4th Alabama Senior Reserve Regiments moved to Cahaba and Montgomery AL. When the City of Montgomery was evacuated, both regiments moved by rail to Columbus GA and took part in defense of the town on Apr 16, 1865. After the disasterous defeat at Columbus GA, most defenders received paroles and went home. Some who escaped capture went home as well.

I'm assuming Hiram Taylor belonged to Underhill's command (4th Alabama Reserves) because his pension application gives that information. The Federal clerk who recorded his parole must have written 45th instead of 4th Alabama. Cannot explain why Hiram Taylor wasn't in service earlier, or why he enrolled in this command.

The 4th Alabama Reserves included a company from Macon County under Capt William A Smith. Smith's company was designed Co "H".