So my staghorn fern, Ned, has been pretty healthy living beside a bright west window with a sheer curtain. I plan to mount him on a piece of wood but haven't found the right one and haven't yet...so we live in southeast coastal Georgia (Savannah) and got touched lightly by hurricane hermine this week. We were forced to leave the house for 3 days because we lost power. I gave most all my plants a little drink before leaving and misted some of the ferns. Upon returning, I saw that Ned has some kind of mold on his basal or shield frond and one frond that looked like it was just dying now appears yellowed and sickly. He also has one frond with a few dark spots and one coming up that looks dead already! I know he needs to be mounted asap but first I probably need to figure out this other situation and I know they're susceptible to fungus so I'm wondering about treatment. I'm attaching multiple pictures of the issues I'm describing. My questions:

1- what is the stuff on the basal frond and can I treat it?

2- does he have a fungus? What's the best and most natural treatment?

3- can he pass any of these issues to neighboring ferns?

thank you all so much!!