Triple antibiotic ointment on the foot is good to use. You can use Original Neosporin or a generic/store brand.
I'd try to source an oral antibiotic like Amoxicillin or Cephalexin, if possible, since they cut the toes off.
Did they use BluKote or something like Hen Healer on the wounds? It somewhat reminds me of blue/green ointments I've used in the past.
It would be good to know what treatments and medications that have been given/used and/or tried.
The yellow stuff looks like it may be pus, but hard to know...
When you get there and actually see the foot, then take photos and we can offer suggestions.
You don't know about the amputation - was the foot damaged from frostbite? OR???
Who knows!!
It still doesn't sound like you know a lot about what's going on? You've not even seen the foot yourself...
Why don't you have your friend open a BYC account so we can deal directly with them if they wish have some suggestions/need help.
A BYC account is free and they can post photos, explain what they have done so far for treatment and can answer and questions directly.