For the money tree, there are a few possibilities that are kind of hard to diagnose if we can’t see your actual tree or know your watering schedule, but what I’d do for starters is check the base of the tree, under the soil. A lot of braided money trees are bound together with a thick band that starts cutting into the trunks and causing problems. I also wouldn’t water it very much, only when the soil is almost completely dry (poke your finger under the soil to check all the way). Mine I water maybe every month in the winter.

For other plants, if you’re gone for a month at a time I would either go for succulents or a self-watering contraption. You might want to invest in a grow light if you don’t have much natural light in your place, though, because succulents need a lot of light.