Hey Siraz,
I don't know about Mary's husbands name. There is a Mary Seery who was the daughter of Jeremiah and Winifred though then her son's name should different, Esther and James are her siblings. I have Esther's baptisimal information below. They were baptised if St. Nicolas of Myra on Francis St. in Dublin and there was a John Seery as well.
/1896-1899. 1949- Seery, Esther Mary- Jeremiah Seery, Anne Tierney (15 Coombe St) Sponsers: John Seery, Mary Seery- Dob: 24/03/1898 Bap:27/03/1898
2/1893-1896. 1116- Seery, John Joseph - Jeremiah Seery, Anne Tierney (15 Coombe St) Sponsers: Thomas Nolan, Anne Smyth Dob: 27/12/1894 Bap:31/12/1894
Jeremiah Seery, 6 there, is named after his grandfather and is Mary's Son. So if you don't know a Jeremiah then maybe it's not the same one. ( I know his birth info is at
https://familysearch.org/pal:/MM9.1.1/FBL6-FZK so next time I'm in town I can check the general register's office for the fathers name) Though there is also the chance he could have died young. I came across a reference of a Jeremiah marrying in the 30's though which might be him.
Jeremiah Seery
Date of Registration: Jan-Feb-Mar 1936
Registration district: Dublin South
Volume: 2
Page: 445
The 1901 census info for these Seery's (Again misspelled and with Jeremiah spelt wrong) is
http://www.census.nationalarchives.ie/pages/1901/Dublin/Merchants_Quay/Coombe_Street/1344461/It could be a seperate branch of the tree going back further though.