To confirm these different sub-inspector Thomas Smiths, I followed up a little further - Thomas Smith (1) born 'City of Dublin', wife born County Limerick, served mostly in the mid-west including County Kerry. This Thomas is mentioned is several newspaper articles including one on his death in 1893 which mentions served 20 years in County Kerry. The informant on the death is a son Thomas.
Your Thomas (2) is the one born County Meath, wife born 'Dublin' served several counties including Tyrone and Wicklow, retired 1st August 1875, his pension record mentions Wicklow, and a page includes a reference to his date of death, and a note stating '..balance paid to Frances Jane Smith, his daughter..', the date matches that death registered off Leeson Park in Dublin - also in 1893.
I'm not sure if the biography details have been mixed up...neither died in Ballina...
Senior Officers seem to be listed in the records separately, and I see no mention of the usual service numbers, which can make it difficult to trace them - especially when there are 'duplicate' names.
The 'Courtown' reference that Elwyn found mentions County Westmeath, which is adjacent to County Meath - this does not seem to an official placename as there's no town or townland of that name that I can see in Westmeath, it could be a local placename, or the name of a house/estate... The placename database includes a location in Co. County Meath named Courtown, this is shown as a sub-townland, or local name, it's located west of the town of Navan and is within Meadstown townland, which is in Clonmacduff civil parish.
Back to the original questions...
After he transferred to Co. Wicklow Thomas served in Wicklow town, families usually lived nearby. I dont see any mention of him serving in other nearby stations - directory lists (Thom's) show him posted as Sub-inspector in Wicklow town right up to 1875 when he retired. As a senior officer he may have been required to attend courts in nearby areas to testify. Kingstown Co. Dublin, now Dún Laoghaire, was part of the Dublin Metropolitan Police area, a seperate but related force.
What's the last documented evidence you have on Frances after the baptisms of the children ?
If she died after the start of civil registration of deaths in 1864, her death should have been registered - and I would think as a senior police officer Thomas would have been well aware of the process. Wicklow town is in Rathdrum registration district, and over the period 1872 to 1893, when Thomas is shown as a widower on his death, there are no Frances Smith deaths listed for the Rathdrum district.
Extending the search area north brings us to Rathdown district which covered north County Wicklow (inc. Bray) and south east County Dublin (inc. Monkstown, Stepaside etc) shows 4 deaths of Frances Smith - one of these is too young and unmarried, another is a widow in Killiney, There are two additional death which do not have register images available yet on the IrishGenealogy website - one in 1879 reported age 65, so born c1807, and another that seems a little too young who died 1876 reported age 48 (c1828).
There are about 11 deaths in Dublin city districts (Dublin North & South) including three without register images ... I looked through the others to check, but none of these match, either ages/est. year of birth did not fit, they were unmarried or widow, or occupation/occupation of husband did not match..
It's worth keeping an eye out for updates to the IrishGenealogy website to check the details of the earlier deaths to see if one of these could match your Frances.
p.s. you mentioned in the other post that you found Thomas living in Dublin in 1884 - what was the source of this information ? also if you have the address that could help searching for further details...