I'll give you the benefit of the doubt here, as people magazine made the same mistake, and fail to realize that she was charged with multiple crimes, including selling meth in front of a school. Their retraction says:

Correction: The original version of this article falsely stated that Tanya McDowell was sentenced to five years in prison solely after larceny conviction for falsifying her son’s address to get him into a neighboring school district. The sentence, which came after a plea agreement, actually encompassed three crimes to which McDowell pleaded guilty: Larceny and two counts of sale of narcotics.

People have expressed wonder as to why a school district would try to press charges against a homeless woman, who was trying to send her child to a school.

Tanya McDowell, who became a sympathetic national figure after being charged in April with stealing the education of her young son from the Norwalk school district, offered a Stamford undercover officer crack cocaine, marijuana and the use of prostitutes McDowell was pimping from her aunt's home in Bridgeport, according to warrants for her arrest.

Perhaps they wanted this pimp and drug dealer not to be near their children. She sold crack outside a school, while pimping (I' not sure exactly who is pimped out by homeless people, and I don't think I want to know), during a children's birthday party. I can sympathize with people who wanted her gone.

The Snopes article fails to mention she was sentenced for drug crimes. Snopes writes:

McDowell was sentenced to five years in prison and five years probation after being convicted of first-degree larceny in the school case as part of a plea deal struck with prosecutors.

That is technically true, but misleading, as she got that sentence as a result of the drug crimes. If someone claimed Dylan Roof got life in prison for carrying a gun, that would also be technically true (he was convicted of possessing a firearm during a violent crime) but misleading.