Her marriage to James McCooke is in the General Registry Office index, Belfast and also in the 1st Garvagh records on the Bann Valley site. The Bann Valley site has two other women marrying a James McCook circa 1800. However, they are both called Sarah and Mary Ann is a more common Gordon name. Her daughter, Agnes, called her first daughter Marianne, who when she got married, called herself Mary Anne. Her son, James had a Margaret Anne and a Mary Jane - but also a Sarah! Her other son John only had a Mary Ann. Almost enough proof for her being the wife of my James McCook. But, one of the Sarah's was a Sarah Archibald, and James called one of his sons Archibald! There is also a Mary Ann Cook, aged 34, farmer, unmarried and living alone in Dullaghy in the 1901 census - could be her grand-daughter.
There is noone in Dullaghy with a name similar to McIlhouse or McAleeece, but there is a Robert McAleece in Killyvally and a Susan McAleece in Craigall.
http://person.ancestry.com/tree/27562964/person/240040318483/facts