The only thing the officer ARGUABLY (and it is a weak argument) did wrong was at first telling her she was under arrest for refusing the take the ticket. It happens more than you think, and typically the thing to do is to submit the ticket without signature and let the traffic court deals with it. If its serious, the local prosecutor can charge her for unlawfully resisting the officer in the execution of his duties (sometime loosely referred to as "resisting arrest" even though at that point it does not involve arrest.)
From there, however, his actions are absolutely consistent with the law as she ran from the officer once she understood he was placing her under arrest, leading to a vehicle pursuit. Approaching her with gun drawn is fine under the circumstances. Attempting to take her into custody is absolutely justified. She then physically resists being handcuffed, easily justifying use of the taser.
It looks bad because its an old lady. But other than the contention that he could have just sent the citation in without her signature, officer acted properly every other stpe of the way, imo.
