Your 90 non-O visa does not activate until you enter the country, and this has to be done before 10th Oct 2025. You can also apply for a 60-day extension based on visiting your wife without providing any financial proof. You can also request a 12-month extension, which has to be done within the last 30 days of your initial stay. For this, you need 400k baht in a Thai bank account in your name, and the funds must come from outside of Thailand. Once you have applied for this, you will get an under consideration stamp in your passport. This is usually for 30 days, but can be 60. During this consideration period, you can purchase a re-entry permit, allowing you to leave Thailand and return without obtaining another visa.
The first 24 hours of an overstay the fine is waived. If more than 24 hours then the fine is 500 baht per day, plus the first day, The maximum fine is capped at 20,000 baht
They do visits for marriage extensions to establish if the relationship is real and not a marriage of convenience. You must get a neighbour or the village head to confirm you live at the address. I've no idea why they would visit a retiree.