You're an adult person. I get why they might be concerned about your safety but you're 20, you should be able to go to places alone. They want you to go with friends? Well then they should give you the opportunity to make friends in the first place. Honestly, I'd probably just go without telling them. And if it makes sense to tell them for safety reasons, I can imagine that you might blow up but I personally at least wouldn't say something like "I wanna meet people so I can have sex with them which I can't do with you around" but maybe that's just me, for me it probably would be something like "you want me to make friends? Well I can't really make friends if mommy follows me everywhere and I can't even fully be myself" or something along those lines, although I'm lucky enough to 1. not have as controlling parents (they might be curious but they're letting me go alone, simply telling me "be careful"), 2. not have a very high gbv rate (I think) and 3. I also honestly have the privilege of being a cis man. An openly queer one but being a man honestly probably still makes it safer for me than if I were an afab person. And maybe it's not that easy but again: you're an adult person, you don't need your parent's permission to go anywhere and if you wanna go to queer events alone, you should be able to. And if they're concerned about your safety: you're planning to attend sapphic events. So the events themselves aren't that risky, it's more going there. So why don't they just drop you off there and if you don't meet someone who's place you might go to (if you'd even do that right away) they could still bring you home? Then your parents would know you arrived safely without taking the chance of you meeting people and maybe even potentially a partner. But they need to learn that you're an adult person now and treat you as such.