The Maughold parish register has this spelling for their marriage:
James Callow & Elinor Cain married 31 Dec 1829.

Their three children bapt Ramsey:
James 2 Aug.1831.
John 12 Dec.1833
Elenor 5 Oct.1836

Marriage Maughold par reg:
14 Aug 1862
James CALLOW, Full age, Bachelor, Watchmaker, [residence] Ramsey, [father] James Callow, Ropemaker and
Elinor CHRISTIAN, Full age, Spinster, [residence] Maughold, [father] Evan Christian, Farmer.

Maughold par reg:
Elinor CALLOW, Ramsey, buried Sep 23 1846.

[Donna's] MI transcript:
"In memory of ELEANOR CALLOW of Ramsey who died September 20th 1846 aged 50 years".
If accurate, she was b.c.1796.

In 1846 both John and Elenor were still underage (under aged 14) so would usually have supervisors "on the mother's side" either given in her will or appointed by the court if no will (by decree). This looks a good possibility to be her will:
CALLOW, Elinor, 1846, Mau, E[pis], [no.] 2, [LDS film no.] 0106446

Sorry but no Elinor Cain bapt 1796-1801 in Maughold records, nor in Ramsey according to the IGI extracted records. Yet her marriage didn't give a different parish for her. Nor did it say she was a widow. There were several possibilities in other parishes.
If you order James's will to view, as suggested previously, it also may mention relatives (hers as well as his).

Sue