I am a qualifying widower but the standard deduction keeps coming up as only 14,900. Isn't my standard deduction supposed to be twice this?

To be a qualified surviving spouse for the two years following the loss of a  spouse, you must have  a qualifying dependent child or step-child--do you have a dependent?  If you can file as a QSS, you get the same standard deduction as a joint return.   If you do not have a dependent to claim then you file Single and get the single standard deduction of $14,600 (+ $1950 if you are 65 or older or legally blind).

https://accountants.intuit.com/support/en-us/help-article/tax-filing-status/claiming-qualified-surviving-spouse-filing-status/L7al83jU1_US_en_US

Using the qualified widow(er) status allows the surviving spouse to file taxes as if they were still married, despite the fact that their partner is deceased. 

• You can file taxes as a qualified widow(er) for the two years following their death.
• Is your spouse still on your tax return?