This task is broken, and have not been fixed by the developers.
It was intended to work like this:
One of the people in the house for Task: Broken Family is on a bed having fever. The doctor says that some herbs might help. This conversation should have started the task, but it doesn't.
The herbs should then be collected from the people in the task series Emergency S.O.S. and Task: Herbal Entrepreneurs after completing the latter. Ryder should have been able to interact with the plants to get a sample, but that is not posssible.
This bug is well-known and has been reported. It is not fixed in the game's final patch 1.10 so we can expect that it never will be fixed unless someone makes a mod to do it (to that end this tool might be useful: https://github.com/GalaxyEham/FrostyToolSuite/wiki).
Update: this mod fixes the quest: https://www.nexusmods.com/masseffectandromeda/mods/541/