(Apologies in advance for this being long!)
It is good that you have had this screening so you can help make sure she catches more of what is going on around her. A lot of what you can do is actually very simple (and very helpful to MANY people). Face her when you talk, get her attention first. Make sure the background noise is not interfering or competing with what she needs to hear (you talking for example). Have her repeat back to you what she is supposed to do to check her comprehension. Things like that. Do them all in a natural way so she doesnt feel embarassed.
My son is Deaf and wears hearing aids. He is going to first grade (reading at 2nd/3rd grade level tho) with an interpreter. We lived in CA where he passed his hearing test with flying colors at birth. There was a month as a toddler he could not hear anything. By the time we got him tested however, his hearing came back and was fine. We think maybe he had a cold/congestion but that was weird. Then after we moved to AZ that summer he turned 3, he again seemed to have some hearing loss (not as severe. Just didnt hear things like oven timers, etc which I dont hear either as I am Deaf myself too)
Anyway, we grieved and were shocked and all that, which was kind of surprising because I thought it would be easy since we were deaf and know what it's like, school options, and all that. But it was still a very tough time for us. Just trying to find out WHERE to go, WHAT to do, WHO to see, man, that was not fun! And unfortunately I am in AZ and cannot tell you where to go, who to see in CA, so I am not a lot of help here. I do want to help you though so please feel free to send me a message and ask whatever questions you may have if you are reading this.
C., you are your child's best advocate when it comes to her education. If your daughter's hearing loss is a permanent one and severe enough, then probably hearing aids (which I suspect will NOT be the case here for her. You'll have to find out from the audiologist & ENT what's going on in her case. )
You ask what options are for correcting a partial hearing loss - if it is a permanent loss, most likely hearing aids, if it's a significant enough loss. (In AZ, there is a place - Children's Rehabilitative Services (CRS) that provides free hearing aids & care. Not sure if CA has an equivalent.)
Since she has a partial loss, not a complete loss, don't go for Cochlear Implants (CI's). CI's were designed for those who had hearing then lost ALL hearing and it is a major surgery coupled with therapy to re-learn how to hear. Hearing aids you just wear (or not) and that's that. Hearing aids are far cheaper than CI's and far less risky, but insurance companies and sponsors often cover the cost for CI's but not hearing aids, which makes me mad.
I need hearing aids as one of mine is broken now but insurance wont cover it. They will cover a CI though but I dont want to lose what hearing I *do* have in order to get a CI that may (or may not) work. I am not opposed to CI's as I have friends that have them and I even have considered them but I do feel it is a major decision to be made, and it is NOT a "fix" as the child with a CI is STILL deaf and STILL benefits from signing and other skills.
A CI is not for me since hearing aids work fine for me, I *love* listening to music and my little boy. I cannot lipread to save my life without also having my hearing aids!! :-P Anybody out there that works in the health insurance/legislative/medical fields, please help make this change!
Make sure you work with someone that is EXPERIENCED & GOOD at testing toddlers! AARGH I still remember the frustration at repeated testing because they were 'inconclusive' and all because the thing they put in his ear kept falling out as he wriggled during the test! stupid!
Go to your school district - you should already know which one you're in ;-) Tell them you need preschool/Early Intervention services and then go from there. They will be able to tell you additional resources in your area, as well as what the school themselves offer. (If you go through them, no charge to you. If you go through your doctor, the bill is yours.)
And a final note. The Deaf community is a wealth of culture and knowledge - do not shy away or "protect" your daughter from it. Pick and choose the best parts of it (which in my opinion is sign language - something everyone should learn at least a little bit of. Start with Signing Time dvd's from the library, your 4yo will probably love it!) Let your daughter be the most she can be, and she can do ANYTHING! There are NO barriers with deafness, only in communicating with sign-impaired people. :-)