A provider I want to see has the latest reviews from Dec 2015. Most of the reviewers are also not active recently. Is the provider trustable?

a gal with more recent reviews from active hobbyists would be more trustworthy.

So, if seeing her would make you feel unsure of your safety, then by all means, select another gal.

Remember, this is supposed to be fun, not nerve wracking.

Based on what you've shared, she's probably legit. Sometimes ladies are still active and just seeing regulars, so no new reviews, or she took a hiatus and you might not hear back if you try to contact her.  If you posted a link to her reviews, we could give you a better assessment.