Best stands so baby doesn't knock speaker over

Anything that’s tall with a narrow base can be knocked over. But if its just tipping over you are worried about, the only real thing you can do is get a wide plant stand with a very large top plate--something probably multiples the size of the speakers themselves. At this point its basically putting them on a small table. Will affect acoustics a bit, but less likely to fall over.

Something like this: https://www.homedepot.com/p/International-Concepts-Mission-Unfinished-Indoor-Plant-Stand-3071/204698858

Just a personal story to share.  I was playing fetch with my dog one day and the ball went into the area where I had my setup.  The speakers I was listening to that day were 17 pounds each and on stands, of course.  So she chases the ball that had gone directly behind one of the speakers.  She gets it, but on her way back up, she gets tangled up in the speaker cable, dropping the speaker.  Luckily and gratefully, nothing happened to her.  She saw it coming and was quick to move out of the way.  The speaker had damage on 2 very sharp opposing corners.  That situation could've been very ugly at the very least.  Yes, the whole thing was my fault.  This could've have also easily been a baby.  Moral of the story:  no speakers on stands EVER around any kids or pets.

Sound anchor stands can be great for babies but if they run into them the baby will get hurt my best advice is keep the baby away from the speakers because any heavy stand will hurt the child i would wall shelf the speakers till the child is older.

You will never childproof anything. Your best reasonable bet is not to have standmounts for a couple of years. It is mostly because children knock them over when running or something like that.

I put some BluTack on my KEF LS50's and stuck them on IKEA toy storage shelves. The LS50 is in my living room which is my sons play room. He listens to music all day like the old man upstairs in the home office. 

I did train him for about 2 years (he is close to 5 now) to not touch the audio gear. So far he has complied.

When he was under 3 years old I used desktop speakers that he could not reach. I should have just used headphones to get better sound.