Sorry to hear about Gran's ulcer.
You state Stage 3 , 6x6. It is draining small amts of serosanguinous, does have some eschar & small necrotic area in center.
Hydrogel is simply water in a gel form which keeps the wound bed moist allowing for autolysis and prevents drying out. It is good , but slowwwww process for any Necrotoc wound.
I've had great response with Mesalt dressing which is a hypertonic 15% Sodium Chloride Impregnated dry dressing , naturally and safely removes debris from wound tissue. It comes as sheets or for leg ulcers and sinus tracts, as a ribbon. Loosely apply the dressing to wound bed, cover with 4x4 and film overlay if on buttocks area or 4x4 and tape. Will really jump start autolytic debridement. Discontinue use when wound bed 90 % pink then return to hydrogel. In wounds with a mixture, sometimes just used Mesalt on slough areas and thin hydrogel on pink skin.
Hope Gran also getting a homecare visiting nurse. Request consult with CETN. If this is a trunk ulcer, she is eligable for a low airloss mattress under Medicare if she has low mobility and difficulty repositioning and can keep 1 to 2 months post wound closure. Make sure you include extra protien in diet to aid wound healing. Viamins with E and Zinc also help wound healing and recomended by several docs at wound centers we deal with. Good luck.
This site has multiple useful links re wound care resources: