Owlbears for 5e at least, should be neutral beasts (or magical beast). They can be trained, but are pretty aggressive by default, which is the very reason some creatures really want them to train up.
In this case, you have the owlbear cave where usually there are the male and female. The male is missing, but still an egg, which means it was likely recent. You have an injured, newly single mother defending her cub and egg.
I think it's reasonable to expect any mother could be hypersensitive at that point about defending her child over her own wellbeing. I wouldn't expect her to be thinking logically about planning for her children more long-term. If she is bitter over prior experiences with humanoids, the loss of the father, her children in danger, I think the situation is completely appropriate. I think her reaction should be to want the strangers to leave them in peace, even if ultimately it means she might and likely would still die. Her own death isn't at the front of her mind, it's the immediate threat.
I don't see anything wrong with the current options and liked it!
