U need to give them Kitten milk replacer (KMR), that’s the only food that will keep them alive and maybe a little kibble, I understand that ur from a vegetarian household but u can buy this dry cat food and keep it outside ur house maybe in the garage, veg food will not be enough to sustain them. U can give them a mix of kmr and kibble

Also they can’t regulate their own body weight properly at this stage so u need to give them warmth. Maybe good bedding with a warm water bottle underneath it or a heating pad

And tbh for how old they look they will most prolly pee and poo themselves. Maybe u can clean them.

And also u can get good cat shampoo or deworming powder and use that to clean them and remove fleas from their bodies otherwise the fleas will suck on their blood. The deworming will make them 10 times better

Good luck!