Without X-rays once only speculate. A dentist should have discussed all of options available for your friend's case.
When finances are an issue, some people will opt for a partial with metal clasps. It is removable and must be kept clean. Your friend needs to ensure proper oral hygiene is being done daily. This means brushing three times and also flossing. Using an antibacterial rinse. Non alcohol if they are a smoker.
With perio disease, keeping the teeth do not sound like an option as they have abscessed. If there is bone loss as well, then again extraction may be the only option. Again, no X-rays, so cannot tell.
I am including a link that explains different types of partials which again are a less expensive route to go, pending there are good, stable teeth adjacent in which to anchor upon.
your dentist can prescribe an antibiotic to get rid of the abscesses and then you hygienist can clean them. also have your friend ask the dentist for a prescription for a mouth wash for his periodontal disease. I believe it is called periodex but dont quote me on that. unless those teeth are beyond repair your dentist should be able to save them just fine. alot of doctors wont even remove teeth if they have an infection at the root. have him ask his dr about an antibiotic and then after the infection is gone his dentist can get a better picture of what the root of the tooth looks like and can decide if an extraction is the best way to go.
Here is a link for the partials I mentioned earlier.
Seems the dentist would have already prescribed any necessary meds upon the initial assessment of your friend.
Meggster the name of the Rx rinse is Peridex.
Good luck to your friend