What would you do?

She's also been a passenger for 40 yrs. So, I'm going to assume, she's pretty aware of the rules of the road. She's not a teenager trying to impress her friends, so she's probably not a speed demon.
Women over 40 are statistically very good drivers, fewer accidents etc than most of the other drivers on the road.
But the true litmus test is whether you've driven with her or not.
That should give you a good idea as to whether or not she's trustworthy.

By road trip, do you mean overnight? In other words, how far is she going, and where will she be driving? Will she be driving on interstates along the east coast Washington to NYC corridor (or anyplace comparable, for example)? If so, I'd have to say no.
I've been driving for thirty years and the last time I drove on 95 through Washington, I almost got run into a concrete abutment by a truck driver who refused to let me merge.
On the other hand, if you guys live out in west Texas and the roads are straight and uncrowded, that'd be different.

Maybe you could go with her and share driving duties.

Also, is she driving alone - in the sense - is there any other adult drivers going to be with her? Do you trust her in general? Is she responsible? Do you trust her with your child besides lack of driving experience?

Let's approach the question this way. How would you respond to this question as written?

Who else is going on this trip? A carload of 5 year olds with a new driver? Nahh.

Regardless of gender or age, two months is not a lot of driving experience and children in the car add a lot to the level of distraction. I'd pass if I were you based on what you've told us so far.