What would be safe to use to kill fleas on kittens 4 1/2 to 5 weeks old?

i have a outdoor cat (she's a stray), she does not like the indoors at all. i did take her a few months ago to a low cost vaccination program and got her vaccines.she had 4 kittens under the house. the kittens have eye infections which i'm treating with tea and they're getting better. i don't have the money to take them to a vet. they're also full of fleas. all i have been able to find on the internet is bathing them and using a flea comb. is apple cider vinegar safe to use on the kittens for the fleas. also, i have a tube of Terramycin antibiotic cream forthe eyes for cats and dogs, but i don't know if i can use that on the kittens, i haven't been able to find anything on that.they might still be too young. and i'm not sure how to put it on them, the package doesn't give you directions. giving them a bath won't work because she'll just take them under the house again. i've tried to put her in an old house we use as storage and work room and she goes nuts. she starts wailing, panting real hard. i've tried several times to leave her in there for an hour or more but she just goes nuts in there. i'm just not sure what to do. i want to help her and the kittens. she does trust me, she lets me hold them and wash their eyes and all kinds of things but she won't stay in the old house where they would be safer and better off. i would appreciate any suggestions, unfortunately i can't afford to take the kittens to the vet.