My DD got very disappointing AS grades in her first year of college, due to anxiety and not settling in/not being happy there and hating the subjects. She made a complete change of subjects and has passed A2s this year. So I do know a bit about A levels and can sympathise with students not doing as well as they hoped.
With that said, I don't want to come across as being negative when everyone else has tried to be positive, but...
"don't worry! She can still get a top grade next year."
this is very optimistic. Yes it is possible to improve overall grades in second year but EXTREMELY difficult and I would say unlikely. No matter how hard you work in second year, AS grades can pull you down if you didn't do that great. My DD got an A in AS media last year and her overall grade this year has come out as a B because she was a few marks off an A in A2 exam. As you can imagine very disappointing!
With your DDs grades I would say she would either need to resit AS modules alongside second year or start new subjects. Please be aware she will not be able to bring grades up to an A without resitting AS, it would be impossible because of the amount of ums marks you need. A bit hard for me to explain here but look into it - you can get an idea of grade boundaries for modules and overall A levels on the exam board website. Ultimately it's about UMS marks from each module adding up to an overall grade so start paying attention to those.
My advice would be to speak to the college about possibly carrying on with Sociology, as that's what she wants to do in future, and raising grade by resitting AS exams and working really hard at A2, and then drop the other subjects completely and start new ones. This would mean she would be doing an A2 and two other subjects next year, and then when she has the full sociology she would have to stay on and complete the other two subjects. This would mean being at college for another two years but that's no big deal.
IMO the above plan would give her a better chance at getting good grades overall and is worth another years work. Believe me, trying to bring three bad grades up to decent ones is very difficult even for the most motivated of students, even with resits. If she hasn't been very motivated this year a lot would have to change next year. Talk to her and try to work out why she has been unmotivated - has she struggled to settle into the college/does she not like the subjects? In this case a change of subjects could be a great idea.
Does DD know what university she wants to go to? Look at entry requirements for the type of unis she wants to get into. Like someone else said AS grades will be important for predicted grades and they are SO important for getting offers. If she wants to go to a top university or RG she will need to be predicted upwards of ABB to get offers. (She may well be let in with lower grades on results day but you need to be predicted high grades to get the initial offer.)
Definitely talk to the college, and if they won't let you carry on with sociology/switch subjects then don't just accept it - look around for different colleges or schools.
Finally, tell her not to feel too down. A levels are really tough and if she's been unmotivated and not done much work she's done well to get the grades she has as they are considered passes at AS. All is not lost, she can still go on to succeed in the future as long as you make careful decisions about what to do next and ensure that her approach to work is different next year. Best of luck 