I would definitely rent a car. The cost will be less than $100 per day, but that will still be cheaper than negotiating a party as a Limo client.
I have driven the 60 mile one-way trip from Las Vegas to Pahrump over 50 times and the traffic is never extremely bad, but I’m used to Los Angeles area traffic that is horrible. It’s only two lane in most parts, but it only takes less that an hour. However, watch your speed in reduced speed areas because the Clark County Sheriff will readily ticket speeders. Once you cross the county line into Nye County the Nye County Sheriff isn’t quite as bad but they won’t tolerate excessive speed either.
Take HWY160 west from Las Vegas to Pahrump. Turn left on Manse and then left again on Homestead Road, or for another route take HWY160 west and turn left on Homestead Road to the dead end where Sheri’s Ranch is located.