According to the Bible the only ‘unforgivable sin’ is rejection of Jesus. The assumption of an ‘unforgivable sin’ is that you can’t ask for forgiveness in front of a pastor/priest.
The young lady met her death on her own terms. There was no healing, and death was coming no matter what. She just chose to say ‘enough’. Anyone saying she should suffer just because of someone else’s beliefs should be ashamed.
More precisely, the ‘unforgivable sin’ is blasphemy of the Holy Spirit.
Mark 3:28-29 King James Version
28Verily I say unto you, All sins shall be forgiven unto the sons of men, and blasphemies wherewith soever they shall blaspheme:29But he that shall blaspheme against the Holy Ghost hath never forgiveness, but is in danger of eternal damnation.