Hello Christine,
'Ambly' has already pointed out the different Household Schedule Numbers for the Allan family at 11 Candleriggs (No:342), various lodgers at West Vennel Com-Lodging House (No:343 & No:344) & various lodgers at Old Bridge St, common Lodging House (No:345)
Looks like A*y has done it's usual speciality in running several addresses together as one!
This OS 25 Inch, 1892-1905 Map from the National Library of Scotland (nls) shows Candleriggs & West Vennel as separate streets, so I assume the West Vennel Lodging House would be just round the corner from the Allan family at 11 Candleriggs.
http://maps.nls.uk/geo/explore/#zoom=18&lat=56.1143&lon=-3.7912&layers=168 Slide the blue Dot on the left of the screen for an up-to-date satellite overview of Alloa. Looks like the West Vennel has gone, although East Vennel on the opposite side of Candleriggs is still there.
Regards, Dod.
Added. Sorry DonM. Hadn't realised you'd already posted a map. I've tried Google maps, Street view, but Candleriggs seems closed to traffic.