A spokesman from Shaw Healthcare on behalf of the home said the allegation was being taken "extremely seriously".
Members of staff connected to the incident have since been suspended, pending the outcome of a police and our own investigation.
We acknowledge the anxiety and distress that this has caused the resident and their family and we also wanted to have the opportunity to reassure the other residents and families so have held meetings to update them on the situation and let them know that we are taking the matter extremely seriously."
A previous CQC inspection of The Granary highlighted some areas for improvement, but the care home owners say it is "unrelated to the current situation."
More top news
Comedian Ricky Gervais will give the profits of his next warm-up gig to a dog charity in Devon. Nowzad rescues strays from Afghanistan.
Major roads in Taunton may start banning cars in favour of pedestrians. The council are hoping to make the town more user friendly.
Alex has the latest weather for Devon, Cornwall, Somerset and Dorset.