Tough love. Assuming all of the support you have obtained (tutoring, etc.) was on track, and assuming she also attempted to meet with the teacher and get extra help (or at least was told to), she has to sink or swim on her own efforts. If she is trying very hard and just can't grasp the concepts, then she needs to repeat the class, either in summer school or by dropping an elective next year (something fun) and repeating the course with younger students. If she's not even trying, then that's even worse.
You say you are "done with her" and I am hoping that is figurative, not literal. I'm assuming that you are a reasonable person who has set benchmarks which she has not met (like talking to the teacher or doing the extra work with a tutor, whatever assistance you put in place). I'm assuming that you aren't really writing off your daughter ("done with her") or abdicating your parental role, and it's just the frustration talking.
The thing is, you need this trip for your job. That's not negotiable. I think, if you have her pay a price now, she will know that you mean business. I think she stays with her grandparents and misses the trip. You're sending the message that work/education are important. She's doing hers, you're doing yours.
If you think she is depressed and that her moodiness/snappishness is the sign of something greater, then you need to get her help for that.
But if you think she's testing you and almost daring you to put your foot down, then put it down.
I have 2 stepdaughters who gave all kinds of warning signs of rebellion. One didn't study and now regrets it ("If I got A's at state college, I could've gotten C's at Harvard. I wish someone had told me to study." -- My husband: "You're joking. I was on you all the time." She sheepishly agreed.) The other got good grades but started running with pretty horrible people (gangs, drug dealers….) and wound up dropping out of college, getting pregnant, and getting into all kinds of legal trouble. She also attempted suicide more than once. But her mother either a) never told my husband about this or b) only told him when his daughter was already missing or hospitalized. We found out about her legal trouble when there was an article in the paper about the disposition of her case. My husband wanted his daughter to get in some serious trouble early on - like not being bailed out for "disturbing the peace" and having to face those consequences. Basically he wanted early intervention while she was a minor (and there was parental control over decisions for her care) rather than waiting until she was 20 and there was no legal way to influence her.
So my advice is to let her be pissed off and inconvenienced and disappointed early in her high school career so that she can turn it around before it affects her long-term record. Colleges are very understanding about a kid who did poorly at first but rose above it and excelled. So a "failure" now is very low risk.
Letting your daughter know that you mean business is really important - when she starts driving and having way more independence, it's much harder to be assertive when she already knows you to be a pushover.
If you have grandparents to supervise her and drive her, that's wonderful. I say, take advantage of it. Tell her you absolutely wish this weren't the case, but it's HER decision not to meet basic requirements, utilize her tutoring well, or whatever other support services you arranged for but she dismissed.
But I reiterate, if there's something else going on from a mental health standpoint, address it. But if she's just going to cop attitude about how miserable you are out to make her, let her know this is within her control, and she can buckle down and get the job done. She'll either buckle down now and actually pass, or she'll stay home from the trip and do the work so she doesn't miss the next vacation.
But DO NOT turn this trip upside down trying to supervise her with on line course work. She needs to be accountable to someone and SHE needs to be inconvenienced, not you.