Sorry to hear about your mom. :(
My mom passed away and there are several kids that will be getting her an annuity for about 9 years. The split is about $600/month for each of us. What is the best way for me to invest/save this? I was thinking of just having it go straight to Vanguard, but I am not sure what fund I would choose. Any ideas?
So you're getting an extra $600/mo.
That's no different than the money you're getting from your job. What if you got a $600/mo raise (and yes, this is going away in 9 years)? Allocate this the same way as savings from your job is currently being allocated. Whether that's paying off debts, increasing a 401k contribution to max it out, sending to taxable cause you've maxed tax advantaged accounts, whatever. There should be no difference with this, as the source of it is irrelevant for your purposes.