Iphone Lost mode text message scam

No. This was a "phishing" message from criminals who have your wife's phone.

By giving them the information they asked for, you have given them what they need to

• Clear Activation Lock – so that they can "make your wife's phone their own" and have a perfectly usable phone to keep for themselves, or resell to someone else.
• Get into your wife's Apple ID account and rifle through any data they can find there.
• Use your wife's Apple ID to log into other Web sites. (Many Web sites allow logging in with Google or with Apple, which makes securing your Google and Apple accounts all that much more important.)
• Try to lock your wife out of any other devices that use the same Apple ID.

You should immediately take steps to regain control of the compromised Apple ID / Apple account.

If you think your Apple Account has been compromised - Apple Support

Also take steps to secure any other account you think may have been compromised.

If the criminals have already cleared Activation Lock (as seems rather likely), it is too late to use Activation Lock to keep them from "making your wife's phone their own." You can still report the theft to the police and to your wife's carrier. If the carrier places the phone on a blacklist, no carrier who honors the blacklist will provide cellular service to that phone again (absent something like you recovering it and showing proof of ownership). The criminals might have a functioning "iPod touch" but carrier blacklisting can keep them from having a functioning "iPhone."

no it's not safe, it's phishing to make you deactivate the activation lock

Recognize and avoid social engineering schemes including phishing messages, phony support calls, and other scams - Apple Support

Identify legitimate emails from the App Store or iTunes Store - Apple Support

Phishing - Wikipedia