Belmullet is the name of a Catholic parish in NW Mayo, and it is also the name of a townland called Belmullet within that parish. The townland of Belmullet is also located within the civil parish of Kilcommon. Civil parishes are very old administrative districts which have lost their connection to the religious parishes (Catholic or Church of Ireland), and don't really serve much purpose anymore, except in some legal references, but lists of townlands are usually arranged by civil parish.
The page you have is from the parish register of Belmullet Catholic parish (I went online to double check that). In case you're interested, you can search the parish register at this link:
https://registers.nli.ie/parishes/0742
You can see more info about the civil parish of Kilcommon at this link, which includes a map of the civil parish, and also a list of the townlands within the civil parish:
https://www.townlands.ie/mayo/kilcommon3/
Looking at the other entries on the parish register page you have makes it clear that they all list townlands within Kilcommon civil parish. You can, for example, see townlands such as Doolagh and Darraragh/Derraragh which are in the list of townlands at the Kilcommon site. In that list, you can also see a series of townlands which start with Muing-, and I suspect that your townland is one of those. It's hard to make out exactly which one, but it might be Muingnabo (spelled as Mungnabo - the anglicized spellings of Irish place names could vary a lot). However, it could also say Mungnalee, although there is no townland of that name. The page for each of the townlands has further links to other info for the townland, such as listings from Griffith's Valuation (mid-1800's). I checked what it said for Muingnabo, but there were no Deane's or Kennedy's shown. You might try checking that for each of the Muing- townlands to see whether such families are shown elsewhere.
Perhaps someone else knows the area and can help out further.
