I am an employee of a fortune 500 company and need emergency funds to prevent foreclosure on my home. I have read some information about hardship withdrawals but want to know if my employer can deny the withdrawal if I meet all the requirements. Is this a federal rule that can't be denied or can this be limited to my employer plan rules? Thanks for the responses in advance and I am aware of any and all negative points regarding hardship withdrawals.

I did a quick Google search on "hardship withdrawals, 401k accounts" and came up with several resources. You might try doing that.
What I could see is that the IRS allows for hardship withdrawals but it doesn't require companies to have them in their 401K plans because it can be a pain to monitor and administer. I have worked for companies that offerer withdrawals and some that didn't. You need to read your company's 401k plan document and see what your options are. With some you can do a hardship withdrawal and some you can do a loan.
If you do a withdrawal it may affect your continued participation in the 401k plan and probably will have tax implications. That should also be spelled out in the document.

Good luck

Preventing a foreclosure does qualify as a hardship withdrawal. But Jeff is correct that a plan does not have to allow withdrawals at all. EVen if it does, I would still look iinto a loan from the plan rather than a withdrawl. IN a 401K loan all the interest you pay is paid back into the plan.