I used to have a 100 mile round-trip. It was only 40 miles on the way in, but that roadway was not rideable later in the day, hence the greater return distance. Once I got used to it, doing both directions five days per week was no big deal. One year I had a little soccer mishap and had to have a leg screwed back together. I spent a few weeks doing the drive in, ride home, ride in, drive home scheme until I had a bit of fitness back.

I strongly recommend good lights, and more than you need. The most reliable ones like Dinotte are a bit expensive, but are still cheaper than an ambulance ride. Someday you will have one (or more) lights fail on you ten miles in. I would also recommend that you make a conscious effort to really push yourself routinely on the way home. Make a mental note of how long it is taking you and try to get faster. In spite of being in my mid-40s at the time, I eventually got (back) to the point of averaging 25 mph. There's nothing like riding hard for lots of miles to improve one's speed.