Are these songs from "My Little Pony: Friendship is Magic"?
These both seem to be fan productions, with songs taken from other sources.
The first song is “Come Little Children,” from the film Hocus Pocus (1993). This is shown in the credits:
The singer is not any one of the actors who voiced Princess Luna, as seen here.
The second song appears to be something called “Daylight’s End” from League of Legends.
The songs were presumably chosen because they made good theme music for the fan animations centered around Princess Luna.