Fenbendazole (Safeguard/Panacur) is the only one I have seen that mentions not to use during molt. There may be others. A lot of people do de-worm during molting since most hens stop laying during this period of time - this way they avoid having to throw away eggs. If a fecal float shows an...
Heavy molting makes them feel unwell and they tend to not eat very good either.
Giving her supportive care is a good idea. See that she is drinking well and eating - even if you need to entice her with a little chopped egg or tuna along with her normal feed.
Find a good poultry vitamin that...