Fleas are running rampant in my mom’s house.

I recently moved back home. My grandpa lied about his dog not having fleas, and left her in the basement area while he went out. Fast forward a few days after he leaves, and there are fleas breeding in the carpet downstairs. All of the cats have them. My childhood cat is white as snow and there are so many flea eggs on her chin that I’m considering going past my mother and taking her to the vet to get treated besides a stupid collar that isn’t doing anything.

What can I get? They have seresto flea collars and they don’t seem to be helping at all. The cats are long haired Maine coons. I’m losing my mind and considering going homeless lowkey because I do NOT want those fleas all in my room.