Is Fluocinonide appropriate to use for foot fungal problems?

Here is more info for you about treatment:
What is the treatment for athlete's foot?

The treatment of athlete's foot can be divided into two parts. The first, and most important part, is to make the infected area less suitable for the athlete's foot fungus to grow. This means keeping the area clean and dry.

Buy shoes that are leather or another breathable material. Occlusive shoe materials, such as vinyl, cause the feet to remain moist, providing an excellent area for the fungus to breed. Likewise, absorbent socks like cotton that wick water away from your feet may help.

Powders, especially medicated powders (such as with miconazole [Lotrimin] or tolnaftate [Tinactin]), can help keep your feet dry. Finally, your feet can be soaked in a drying solution of aluminum acetate (Burow's solution or Domeboro solution). A homemade remedy of dilute white vinegar soaks using one part vinegar and roughly four parts water, once or twice a day as 10-minute foot soaks may aid in treatment.

The second part of treatment is the use of antifungal creams and washes. Many medications are available, including miconazole, econazole nitrate (Spectazole), clotrimazole (Lotrimin), terbinafine (Lamisil) sprays and creams, and ketoconazole shampoo and cream (Nizoral), etc. Ask your health-care professional or pharmacist for a recommendation. Treatment for athlete's foot should generally be continued for four weeks or at least one week after all of the skin symptoms have cleared. More advanced or resistant cases of athlete's foot may require a two- to three-week course of an oral (pill) antifungal like terbinafine (Lamisil), itraconazole (Sporanox), or fluconazole (Diflucan). Laboratory blood tests to make sure there is no liver disease may be required before taking these pills.

Topical corticosteroid creams can act as a fertilizer for fungus and may actually worsen fungal skin infections. These topical steroid medications have no role in treating fungal foot infections. (this is why you dont want to use the Fluocinonide 0.05%-it is a corticosteroid)

If the fungal infection has spread to the toenails, the nails must also be treated to avoid reinfection of the feet. Often, the nails are initially ignored only to find the athlete's foot keeps recurring. It is important to treat all the visible fungus at the same time. Effective nail fungus treatment may be more intensive and require prolonged courses (three to four months) of oral antifungal medications.

What home remedies are available for athlete's foot?

Multiple home remedies are available, including vinegar soaks, dilute Clorox soaks, and shampoos like Head & Shoulders or Selsun Blue. Other reported but unverified remedies have included Vicks Vapor Rub and Epsom salts. Dilute vinegar soaks or sprays (roughly one part white household vinegar to four parts water)
Dilute Clorox baths or soaks (approximately ¼ cup household Clorox bleach in one bathtub of water)
Hope this helps some!

It is for itching and inflammation but it might make the foot fungus worse. Try the Tinactin instead. Be sure you apply as directed and use it for the full time it directs. Foot fungus can be hard to get rid of sometimes. (Sorry to hear about your fathers passing)