what about good old waterbottles with the furry cover on them so they dont burn you, maybe have a look at clothing that skiiers wear, or google special care blankets. make sure she has a few pairs of good woolly socks, a warm hat, warm gloves, thermal underwear etc, or wear longjohns or leggings. a good warm dressing gown she could wear in bed and those flannette sheets are warm too. a good heavy 15 tog feather duvet is lovely and warm too. how about buying one of those gas cylinder mobile heaters and always have a spare cylinder to hand.