This may not be about the 18 year old at all and those that say he needs to get a job are unrealistic and he has to be available for work, or will soon be offered training courses.
Care shifts are either 7/8am-7/8pm, or equivilent nights, so difficult for any single mums.
In the ideal world, the father would be an option, but i take it that isn't the case.
Care work, as said should be done by those that want to do it, not weighed up, like working behind a till. Not everyone can change pads, night shifts are all about cleaning up shit, tbh.
The job doesn't pay sick pay, that is what causes most problems. Go off sick and you cannot pay your rent, you don't earn enough to be better off than on benefits, then.
If she is struggling to feed her children, now. Then she will probably still find it a struggle.