I am on SSD and wife works we have 2 children can she claim Head of Household to prevent wage garnishment in Florida

Who is the Judgment against - you, her, both of you?

“Florida law does provide an exemption which is specific to wage garnishments. This exemption is not automatic and must be claimed by filing an affidavit with the Court when you are notified that the creditor intends to request a wage garnishment. If you properly claim the exemption, your wages cannot be garnished by a judgment creditor if you are head of the family and your wages are $750 per week or less. If you are a head of family and your wages exceed $750 per week, they can only be garnished by a judgment creditor if you have agreed in writing that the creditor can garnish your wages. To qualify as head of family, you must provide more than one half of the support for a child or other dependant.

An example using the exemption:

Jose is married and supports his wife and child, providing more than one half of their support. He works full time and takes home $1,200 per week after taxes. He has not agreed in writing to any garnishments. If Jose claims the head of family exemption, a judgment creditor cannot garnish his wages.”

Florida Wage Garnishment Law | Nolo.com (http://www.nolo.com/legal-encyclopedia/florida-wage-garnishment-law.html)

If the judgment is only against you, then they can't garnish her wages. However, they can attach joint bank accounts. So I would suggest you not use them.