From what little information I can find, it seems to be related to the name Malo, which you can find here:
https://www.behindthename.com/name/malo/submitted
The -aume ending can be seen in a few names of Germanic origin (like Aliaume and Guillaume), that coming from the Germanic element -helm, though Malo is of Breton origin, so maybe the -aume ending in Maleaume could have been influenced by that?
My PNL:
http://www.behindthename.com/pnl/149249My blog:
https://maybeitisdaijirou.wordpress.com