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My try:

5 fevrier 1679 mr ducrocq chanoine clerc a marié par ma permission Pierre Girau....
Simon...moy , joseph ligny
Charles Hoyd, George Hoyd
Sa belle(?) tante...
Marthe Hoyd ,Marguerite Hoyd ses cousines germaines
En foi de quoi...
Mr dumetz...
Dupin..curé dudit st firmin a Montreuil

I am not sure at all about Hoyd , it must be something else , your suggestion about Ohier seems correct to me.

Added: geneanet gives a lot of Ohiers in Montreuil and Neuville sous Montreuil

https://gw.geneanet.org/md2mido01?n=dupouy&oc=&p=jean+dit+le+mougnon+du+bas
here's  the tree

Someone called X dit Y  = X aka Y
in this case Y is a "surnom" in french , this "surnom" could be something like "le jeune", "le vieux" to distinguish the son from the father (X dit le jeune, X dit le vieux), it could be "petit"  or "le petit" to distinguish the small cousin from the tall one , it could be " du pont"  ( X dit "du pont" , living near the bridge) to distinguish him from another X dit "du bois" living near the wood), it could be anything with no explanation for us living in the XXI th century.

Concerning the DUPOUY dit Le Mougnon du Bas  :

1. it could be Dupouy dit Le Mougnon , du bas ( living in the bottom of the village you don't mention)
2.                 Dupouy dit "le Mougnon du Bas "

If le Mougnon is the name of a place , I found only one in France , near Gondrin in Gers departement  :




I also found a Pont Mougnon in the Deux-Sevres departement

The second snippet being  : habrial fancy swirl notaire

the first one may be : troisième et dernier role paraphe ( signed initial for habrial) or paraphe and fancy swirl

The text in the margin says that the mother Marie Clémentine Augustine recognized the child as her daughter ( it was necessary in case of death of the mother , it made the child a legal heir)