Maybe this is where you doubt is regarding Joshua or Joseph..
Joseph Everingham
Christening date: Jul 1770 place: SAINT MARY AND SAINT NICHOLAS,BEVERLEY,YORK,ENGLAND
Father: Joseph Everingham
Indexing No: C10658-2 System: England-ODM Film No: 919421
There dosen't appear to be any other baptism's for children to a Joshua/Joseph Everingham between 1755-1790 so maybe this is or is not the same family, but could this be the Joshua Everingham's baptism:
Joshus Everingham
Baptism 12 May 1714 place: Beverley, Yorkshire
father: Joshua Everingham
mother: Mary Everingham
record set: RG4_2601
England and Wales, Non-Conformist Record Indexes (RG4-8)
https://www.familysearch.org/learn/wiki/en/England_and_Wales_Nonconformist_Index_for_RG_4-8_(Record_Groups_4-8)_(FamilySearch_Historical_Records)
As for her surname
Owbridge is defo a surname and spelt that way too, could any of these be her baptism:
Mary Owbridge
Christening date: 03 Mar 1733 place: PRESTON BY HEDON,YORK,ENGLAND
Father: Jarvis Owbridge
Index No: C10904-2 System: England-ODM Film No: 991178
Church of England. Parish Church of Preston (Yorkshire) 1600-1827
Mary Owbridge
Christening date: 09 Oct 1737 place: PRESTON BY HEDON,YORK,ENGLAND
Father: Bartholomew Owbridge
Index No: C10904-2 System: England-ODM Film No: 991178
Church of England. Parish Church of Preston (Yorkshire) 1600-1827
Mary Owbridge
Christening date: 28 Feb 1711 place: Weighton-Market, York, England
Father: Bartholomew Owbridge
Index No: C10907-3 System: England-ODM Film No: 1068384
Church of England. Parish Church of Weighton-Market (Yorkshire) 1653-1900
The first two entries she would be young enough to have children, the latter she would be airing towards 44 at marriage in 1755 and all in the area for a marriage in Beverley too.
bendywendy