My dad almost died when I was just an infant due to an estranulated hernia. The doctors performed emergency surgery on him in the middle of the night and removed 18 inches of his intestines.
Yes, a hernia can indeed become life threatening if not taken care of.
Glad your Mom is doing okay now. Would rather see her have the hernia fixed than to risk not having it repaired and have worse consequences. Prayers for you and yours.