Fitzcoraldo,
Don't know if these help, but it's a slightly different spelling, confirming the "old woman" translation.

http://www.munromagic.com/MountainInfo.cfm/251
http://walking.visitscotland.com/munros/roytomonadhliath/a_chailleach

I've also seen, somewhere that escapes me, it translated as "the witch".
Cheers,
TE.