Most of the Home Guards units were mustered in for a 90-day period, and dates varied from county to county. Those who served the full 90 days (or their widows) were eligible to apply for a federal pension in 1890. My ancestors served in the Benton Co Regiment, 13 June - 13 Sept 1861, but were not paid until 1863-64. The NPS site at http://www.itd.nps.gov/cwss/soldiers.htm lists following:
Wm. A. Bradshaw (First_Last)
Regiment Name Capt. Bradshaw's Co. G, Osage County Regiment, Missouri H.G.
Side Union
Company G
Soldier's Rank_In Capt.
Soldier's Rank_Out Capt.
Alternate Name
Notes
Film Number M390 roll 5

Your ancestor should be listed also, but try alternate spellings, as errors are common in the rosters.