Bicycle Mechanics - Brake Pad Replacement on old caliper brake mountain bike

I am trying to refurbish my wife's bike to do grocery store runs. It is a 12-year old mountain bike that is in good shape. The only real problem that I am having is getting the brake pads replaced. The bike uses Caliper brakes. I know road bikes use calipers, but I don't know if the brake pads for a road bike will fit on calipers designed for an MTB.

The wheelset is 26 x 1.5", and the only sticker I can find on the brakes says Vanguard. Sorry I don't have pictures, but the pads are screwed into a long slot on the side of the caliper.

If there is any necessary information that I have left out, please let me know, and I will do my best to provide it.

Thanks.

if it is truly an caliper brakes then yes any road caliper brake pads will work for you .

I am trying to refurbish ..a 12-year old mountain bike ..The only real problem that I am having is getting the brake pads replaced. The bike uses Caliper brakes. .

It wasn't too unusual way back when for MTB's(particularly Marin) to use a chunky caliper brake for the rear, mounted under the chain stays. but I've never seen a MTB with a caliper brake for the front. The most similar thing in production today probably are caliper brakes for the BMX market. That's where I'd start to look anyhow.
Ordinary road pads would probably fit, but question is if they would fill up the distance between arm and rim well enough to allow for a good setup.

The name is evading me at the moment, but there is a make of canti brakes with threaded posts that also uses rather chunky pads. They might also be a good candidate.