Yes, if both son's are no longer dependents and the sober living house is considered a medical necessity that health insurance won't cover. Read this link for more info
http://www.401khelpcenter.com/401k_education/hards hip_withdrawal_article.html

The IRS doesn't define a "hardship withdrawal." It allows employers to define a hardship under the 401(k) plan.

Qualifying to take money out of a 401(k) for "hardship" doesn't necessarily get you out of the 10% early distribution penalty. A tax professional would need to know more about your financial situation and the ways you spent the money before giving a definite answer.

When I contacted Fidelity Investments to begin the paperwork process, they felt my son's sober living house expenses qualified under the non-reimburses medical expenses, however, when I contacted my HR retirement department with questions, the person I spoke with said she doubted this qualified under the IRS guidelines and it's up to the IRS, not the employer. I'm frustrated and confused.

Thing is, if your son who needs help with the sober living facility costs is not eligible to be listed on your tax return as a dependent, you can't claim his medical expenses as a deduction, either. You wouldn't be taking a hardship withdrawal for your needs, as this would not be your hardship, but your son's. You'd in effect be taking a withdrawal to fund a gift to help another individual.

"Hardship" is decided by the 401(k) plan.

"Qualifying medical" is decided by the IRS. They have a publication devoted to that subject -- http://www.irs.gov/pub/irs-pdf/p502.pdf . To be of help to you, tax-wise, this would also have to exceed 7.5% of your income.