Final answer:
When a house is left to someone for the duration of another person's life, it is called a life estate pur autre vie.
Step-by-step explanation:
If a person leaves a house to a young lady only for the duration of her grandmother's life, this type of estate is called a life estate. Specifically, it's a life estate pur autre vie, which translates to 'for the life of another.' In this situation, the young lady holds the property for the life span of her grandmother, after which the property may revert to the original owner's estate or another designated person known as the remainderman.