The NHS definition of 'Safeguarding' is:
Safeguarding means protecting a citizen's health, wellbeing and human rights; enabling them to live free from harm, abuse and neglect.
So, yes, there is a safeguarding issue here - the health and well being of OP and her DH. From what she has said about herself and her DH and the fact that, in her words, the house is 'shambolic', I think would cause a casual visitor to the house who did not know them, to be concerned that there might be a safeguarding issue and Social Services were right to check.
As it happens the household is managing nicely, so the OP should be gracefully thanking them for their enquiry but reassure them that all is fine - and be glad that these checks are being made, because many households like hers are struggling and do not know where to get help and and a call from Social Services is what is desperately needed.
As we get older many of us do become more reliant on other people to help us, but it is very difficult for those dealing with older people, as a group to know, unless they have met them, who needs help and who doesn't, so to have a policy of asking people if they need help, rather than wait for them to ask them, strikes me as being proactive, empathetic and considerate.
As I said, I was rung up by the hospital before minor surgery to see if I needed a wheeelchair to get from the entrance to the ward. I didn't, and was monetarily disconcerted by the question, but quickly realised how, if I had needed it I might well have been worrying about how to get from hospital entrance to the ward, not known whether wheelchairs were available, and worrying myself unduly.