Chewbacca
Hang on a minute.... If your daughter in law is home schooling your grandchildren, how do you expect her to go out and get a job? Are you suggesting that she could get a job and work from home at the same time as home schooling the children? If so, yes, you are being u reasonable. Or are you suggesting that your son and his wife should give up their principles of wanting to home school their children, send them to a state school and send the wife out to work? If so, yes, you are being unreasonable because how they run their home is nothing whatsoever to do with you. Please, under no circumstances, lend/give/donate them any money. The resentment you feel, and which is clearly showing in your post, will eat away at you and your son and his family will feel beholden to you forever. Money, whether given or gifted, should be with no strings attached, no judgements and certainly no resentment. Keep your money in your pocket Betty25.
All of that that!
Plus, if your son could only "just" afford the repayments on a mortgage, he might struggle very much as the cost of living crisis deepens, especially if it lasts any length of time (assuming you are in the uk).
Would you then be prepared to help out on a regular basis if 'just' were to become 'not quite'? If it was your generosity that got them into that situation, there might be a certain amount of moral obligation ...