I'm going to tell my parents not to go to a grandmother's funeral because the place is unsafe
What exactly do you mean to tell them?
The place they are hosting it has a really high crime rate.
They're your parents and it's a grandparent's funeral!  You need to trust them enough to make informed decisions about things that important.  I'm sure they'll be fine!
If they care so much about me they should do what I ask. I don't want them to go to a place that's unsafe.
The likely hood of something bad happening is super low anyways. IF you feel unsafe you could hire private security or bring pepper spray.