1891 census has Oliver O Clarke age 35, stonemason, Bristol Rd, Northfield (would have included Selly Oak), born Birmingham.
Oliver Owen Clarke was born 3rd q. 1855; married Elizabeth Turner from Claines, Worcester in Droitwich district (which included part of Claines then) 2nd q. 1879; and died aged 43 2nd q 1899.
They had (amongst others) a son, Oliver Turner Clarke, in 3rd quarter 1883, who married in Birmingham 4th q.1903 (to Lillie Gillard or Kate Grady).
An Oliver Clarke is at 22 Luton Rd Selly Oak in the 1912 electoral roll, but a different name is there from 1920 onwards.
Only widow Elizabeth Clarke is at that address in the 1911 census, although a missing name, aged 29 has details crossed out above hers and ner occupation of 'mother' is altered to 'housekeeper' or 'visitor', she being the only person listed.
There is an Oliver T Clarke in the WW1 medal rolls, a gunner in the Royal Garrison Artillery. Might be him, might not.
That should date your stone to 1880-1900, the same as mikejee's notes from Kelly's.