Your pointer to AMyHUD is invalid. Do you check its not null before using it? No you do not! 
Seriously, NEVER use a pointer without that check.
I’d not put the nLivesRemaining on the character btw… because that is going to be destroyed. The best place to put this is in the game mode class. Hook the actor destroyed event and if any of your important objects get destroyed decrement the nLivesRemaining count and respawn the actor there.
Game mode is basically the place where you’re game logic is meant to be. So its ideal for this kind of thing.