@Glenn *********
given she's just had a baby perhaps a 10 plus minivan trip to the border isn't in her best interest 😮
I think the easiest solution is to just bounce her out/back by air
Buy a one way ticket to KL in the morning and a one way ticket back to Bangkok that same afternoon (you can't buy round trip with really tight time points)
Fly her down to KL, stamp her in and out of malaysia, then fly her back to bangkok that same afternoon,
Have her present her passport and DTV to the officer when she stamps in and she'll get a new 180 day entry stamp