Beta mission 5...noooope.
I'll entertain your notion of destroying these scattered goo nests, but I'm not going to hunt down those remaining mother goos. They can survive a Ruk nuking to the face and just slither off to recover before I can nuke them again, if I'm even lucky enough to find them again. That in and of itself wouldn't be too bad, were it not for the fact that they keep reproducing. The mission ceased being fun when I realized that by the time I find another mother, on the opposite end of the map another one is going to pop up. This is pure-grade tedium.
Probably done with the campaign unless it delivers in huge ways down the line.
No how on earth do you do that?
Build a repair pad. Believe it or not, the Hand of Ruk counts as a ground unit. Once you do that, you can keep your Hands of Ruk healthy for killing some Goo.
Also, bulding a medium hub with two hangars and 6-8 bomber jets will help immensly with taking out those pesky Mother Goos. Just be aware that in the top right corner of the map is where the Goo are concentrated the most. Bringing your Hands of Ruk to help quell that section of the map will help a lot.
There will come a point where eventually you won't have to worry about your base defense, and you can just invest all your resources and squad cap on units specifically to take out the straggling Goo. Also remember that your Hands of Ruk can also pump out units. Once I have them on the attack, I just have them rotate between two Predators and two Stalkers and rally them right on the Hands so that they join the fight immediately.
It is tedious, but you can get through it.