I have not deposited the earnest money yet.

The repayment terms for a 401k participant loan are equal monthly/quarterly payments of principal and interest (typically prime plus 1%) over a 5 year term (longer if used to acquire your principal residence).Please note that if you take a full $50,000 and then pay back the loan, you can't take another $50,000 until 12 months after the first loan was fully paid back.Per the loan offset rules that went into effect with the 2018 Tax and Job Act: if you leave your job and the loan is current at the time you leave your job but then the loan goes into default because you left your job, you will have until your tax return deadline (including any timely filed extension) to make the loan current by depositing the outstanding balance into an IRA (and thereby avoid the taxes and penalties that would otherwise apply).Please keep in mind the multiple loan rules:Under those rules, the sum of the balances of a participant's outstanding 401k loans under a single 401k plan (using the highest outstanding balance of each loan over the last 12 months) can't exceed 50% or $50,000 whichever is less.

The security deposit balance will be mailed to you within 14 days after you return possession to the forwarding address that you provide to us.Tenant(s) furthermore expressly agree to pay for such cleaning and for any repairs needed as outlined on the Move-Out Charge Sheet.

His wife had given me the address in hopes of receiving a deposit. 

If the tenants were good in their previous rental, they should get most if not all of that deposit back. 

All the property management that I dealt with had the rental income deposited into their account not mine.

She must have given you a deposit and at least some rent at lease signing?

Well, I'll quote FannieMae.com directly here:"Borrowed funds secured by an asset are an acceptable source of funds for the down payment, closing costs, and reserves, since borrowed funds secured by an asset represent a return of equity.Assets that may be used to secure funds include automobiles, artwork, collectibles, real estate, or financial assets, such as savings accounts, certificates of deposit, stocks, bonds, and 401(k) accounts."

Offer to help them find a new place and pay deposit on it, for example?

I remember hearing on a Bp podcast about putting down $100,000.00 as a deposit would sweeten the offer, and that as long a I have my contingencies in place I should be fine.