If they serve you and obtain a judgment they could attach a lien. You may or may not meet certain exemptions that would not allow them to do so.
In any event, be advised that Midland Funding is not a collector for the entity which issued your husband a credit card. They purchased the right of assignment from the credit card issuer and now own the account. They are a debt purchaser who paid probably 2 to 5 cents on the dollar for the account.
Moreover, they do not have proper standing to sue anyone in Tennessee. That isn't to say that they don't, rather than upon filing a motion to dismiss they lose for lack of proper filings with the secretary of state.
An aside, I am presuming that once you are served you will be dealing with a debt collection out of Little Rock, Arkansas. You can call the General Sessions Court Clerk - Civil Division in Putnam County to verify this.
You may want to seek an attorney who practices consumer litigation in the mid-state. If you want someone local, Mike O'Meara is good although I don't know if he represents people in actions such as these.
Barnette Law Offices
309 Hollow Tree Court
Nashville, Tennessee 37221
They likely will not be able to take your van, but they may be able to attached a lien to your vehicle which would be required to be paid if you ever attempted to sell the van. You should contact a TN bankruptcy attorney, as they will be able to inform you of the creditors' collection options and your debt relief options. I am not suggesting you need to file bankruptcy, but you should seek advice regarding your legal rights.