I believe it is possible that Mary married a second time after the death of George Nugent. There is a record of marriage in 1929 between a Mary Hogg and Frederick Corteen, indicating she was a widow at the time. I also believe she married a third time to an "unknown McGarry" (as mentioned in Frederick's Will).

Mary Hogg
Record type: Marriages

Parish: Braddan

Gender: Female

Marriage date: 19 December 1829

Marital status: Widowed

Spouse: Frederick Corteen

Spouse marital status: Bachelor

Register identifier: MS09073/3/3part2

I've also located a Will in the name of Frederick Corteen in which he mentions his wife, Mary (Hogg) Corteen:

Submitted by: for Tom Corteen
Date: 22 January 2008
Original: Manx Heritage

In the Name of God Amen
This is affirmed to be the last Will and
Testament of Frederick Cotteen of the Town of
Douglas who being at present weak in Body
but of sound mind memory and understanding
Do hereby make and Declare this paper writing
to be my last Will and Testament. Hereby
[Re]voking and making void all and every other
will or will by me heretofore made.
First I commit my soul to God and my Body

to a Christian Burial.
Secondly I leave and Bequeath to all persons

who shall or may claim to this my last Will

and Testament the sum of one shilling each

as legacy.
Thirdly I Give [Devise] and Bequeath unto my

loving wife Mary Cotteen otherwise Hogg

otherwise McGarry my whole right title

and Interest in and into a certain

dwelling house and back yard to the same

belonging and adjoining situate lying and

being in Kk Michael street in the Town of

Peel To Hold the same unto the said Mary

Cotteen my wife her Heirs and Assigns for

ever
Fourthly and Lastly I Do hereby Nominate Constitute

and appoint the said Mary Cotteen

my Wife Whole and Sole Executrix and

Residuary Legatee of all my Goods and

credits and effects of any Kind or Denomination

whatsoever and wheresoever moveable and

immoveable whether real or personal

and this I make as and for my last Will

and Testament. As witness my name and

mark hereunto subscribed by my consent

the Thirteenth day of March, One thousand

eight Hundred and Forty three 1843
Signed and Declared
etc
Thos Clague
Robert Radcliffe
Frederick Cotteen my X mark

At a Chapter Court held
at Douglas 14th June 1843
Mary Corteen the Executrix named
in the will is sworn in court in
form of law well and truly to execute
the last Will and Testament of
Frederick Corteen decd and to these
ends hath given pledges for
the payment of Debts and Legacies
namely Joseph Hogg of Douglas
in the parish of Onchan and
Thomas Clague of Douglas
in sd parish of Onchan
Best of luck,

Pat G