Not to beat a dead horse if you think you got this...but....
I have a client who works for Tesla. They get quarterly awards of stock options. Tesla is very good about giving the worker all the details of the awards, so it is just a matter of hunting for the award date and the amount of income that was included for that lot when it was awarded. Just finished that return last week.
From your original post above, it is not clear that the client has "sold" the stocks, just exercised the right to purchase the stocks. If that is the case, then there will not be a 1099B. At the point of grant (not exercise of grant, but the grant of the options), there is generally no reporting, because there is nothing of value that has changed hands. The employee has the option, but not the requirement, to purchase the shares at a given price (the option price). If they don't actually choose to purchase, they have received nothing from their employer. This is what it sounds like happened to your client. Then, when she was leaving the company, she exercised the options, purchasing shares at a discount to the FMV on that date. The amount she gave the company (the option price) is basis, as well as the spread between the option price and the FMV on the date of exercise of the option. The spread is the portion that should be included in the W2 at ordinary rates. This is also the amount you need to hold on to for the actual sale of the stocks when it happens, because the broker may or may not have the correct basis reported on the 1099B.
If there is no 1099B, then there is no sale. Double check with your client that they did not receive a check. If she got a check, she should also get the corresponding 1099B.
In a lot of cases, the grant, the exercise and the sale all happen on the same day. Even in this case, there should be a 1099B. It generally results in a small CG loss due to the broker commission (as Judy said above).
Back to your original problem. The real question is: Did she sell? If so, make her get the brokerage statement. If not, then ask her where the stocks are held right now, because she owns them and some broker is holding them in an account with her name on it.
Hope this is clear as mud for you?
Tom
Modesto, CA