You want to Move the data in the change node, and as the influxdb node requires it to be in msg.payload, you need to put it there...
[{"id":"1840b612.f851ba","type":"inject","z":"edaf3fb5.1907c","name":"","topic":"tele/Wemos/SENSOR","payload":"{\"Time\":\"2019-07-16T07:16:50\",\"DS18B20-1\":{\"Id\":\"0317714CDDFF\",\"Temperature\":21.9},\"DS18B20-2\":{\"Id\":\"0416A23873FF\",\"Temperature\":22},\"TempUnit\":\"C\"}","payloadType":"str","repeat":"","crontab":"","once":false,"onceDelay":0.1,"x":179,"y":207,"wires":[["c214567f.495a7"]]},{"id":"c214567f.495a7","type":"json","z":"edaf3fb5.1907c","name":"","property":"payload","action":"","pretty":false,"x":319,"y":267,"wires":[["e31939e1.54ac68"]]},{"id":"e31939e1.54ac68","type":"change","z":"edaf3fb5.1907c","name":"","rules":[{"t":"move","p":"payload[\"DS18B20-1\"].Temperature","pt":"msg","to":"payload.DS18B20-1","tot":"msg"},{"t":"move","p":"payload[\"DS18B20-2\"].Temperature","pt":"msg","to":"payload.DS18B20-2","tot":"msg"}],"action":"","property":"","from":"","to":"","reg":false,"x":489,"y":227,"wires":[["66fce211.fa0b44"]]},{"id":"66fce211.fa0b44","type":"debug","z":"edaf3fb5.1907c","name":"debuginfo","active":true,"tosidebar":true,"console":false,"tostatus":false,"complete":"true","x":669,"y":207,"wires":[]}]
