They should explain properly. Especially "stealing" part. Grandma didn't stole it,they made a mistake, it's their fault. Mavikelebek
The grandma did steal it. That's why she was crying. She's so obsessed with her grandson not dying like her husband and son, that she pretended to be sick while taking a break at the temple and took that opportunity to look through their medicine and steal what she thought was the best one.
If those monks do a shoddy job of explaining the situation and a misunderstanding ensues that leads to him disliking her I WILL SCREAM! ヽ(`Д´)ノ