I assume that the road which was closed was the Tioga Pass road.

Generally, if you are going to Yosemite Valley, which is much lower down and does not require a high altitude pass crossing, you should not have snow problems in October.

And, more on topic, I would certainly reserve ahead. Not because you won't find a place in L.A. on arrival, but because you can save a lot of money that way.

Even Motel 6 has internet discounts. Even if you don't have a laptop with you, you can usually go to the local public library to access the internet for free and make your reservations.