My choice for Squamous Cell Carcinoma was guided by the central location of the tumor. To me, that didn’t look like the cavity you’d get with abscess but a huge tumor.
The clues for trichotillomania were the death of her grandmother suddenly, since trichotillomania is often stress-induced. I also narrowed it down by it saying the hair was in different growth stages in the patchy areas, which makes sense if she’s plucking them out at different times.
Telogen effluvium is most common in middle-aged women, so she doesn’t fit the profile (but you’re right about it being caused by stress).