I believe she has 2 bettas -- 1 male, 1 female -- if I remember correctly from her earlier posts, and 4 tetras, not 'betas'.
If I'm correct in that, I would recommend -- first of all, as everyone else has said, ID'ing the 'algae eaters' and catfish to determine if anything should be added... then, if so, adding at least a couple more tetras. What kind of tetras are they -- small, like neons, or larger, like black skirts or serpae tetras? The kind of tetra makes a difference.
As to the mollies, are they both male, or a male and a female? If the latter, you'd be better off adding a second female, maybe even a third, to spread the male's attentions around and keep the lone female from being harassed to death.
To answer your stocking questions it's essential to get a more precise fish ID first. Post up pics of your fish if you have trouble with this.