Hi, sorry took a while to get the info for you. Mullen in 1911 MULLAN in 1911.
I hope this a help, seems they were in the town of Managhan.
Name James Mullen Event Type Burial Event Place Monaghan, , County Monaghan, Ireland
Latlurcan Old Graveyard
Name Anne Mullen Event Type Burial Event Place Monaghan, , County Monaghan, Ireland
Latlurcan Old Graveyard
The Church
http://www.buildingsofireland.ie/niah/search.jsp?type=record&county=MO®no=41400977
Margaret’s marriage. Says Market Street Monaghan. (I used the marriage to find the rest of the links)
1901 Census in Ireland
http://www.census.nationalarchives.ie/pages/1901/Monaghan/Monaghan_Rural/Market_Street/1638790/
1911 Census in Ireland
http://www.census.nationalarchives.ie/pages/1911/Monaghan/Monaghan_Urban/Market_Street/811153/
The marriage of James and Anne McAleer
https://civilrecords.irishgenealogy.ie/churchrecords/images/marriage_returns/marriages_1871/11354/8168325.pdf
If you paste the links into google/search you will see the documents.
Have a nice trip next year
Margot