How/to whom do I contact about getting SS to help out with MIL's care?

Yes, I think you mean Social Services. You should have a County Office. If Mom is receiving SS then she is receiving Medicare. Neither help with in home care. Medicaid might if Mom is low income and fits the criteria. Even, just getting Medicaid for health insurance will help. There is also SSI which is a supplimental income which she may qualify for. Social Services has a number of programs. So make an appointment and see how they can help. Try your County Office of Aging too. They help with transportation and Aides.

You need Social Services not Social Security.

You or the person who suggested it may be mixing up SS and Medicare, Medicaid and or state programs. Which brings up another import piece to the puzzle, much of what is available to your MIL will depend on the state you are in. I would start with her primary medical provider, many offices that have geriatric clientele either have a person who helps coordinate these things or at least are knowledgeable about where to guide you to find info. Unless you tell them about your needs, what you can or can’t do to meet her needs they don’t suggest help, remember some of their patients and families don’t want (or don’t think they want) outside help and they have no way of knowing who needs financial help unless you tell them. In some ways I guess it’s being responsible not encouraging families to use assistance who don’t really need it, that way more is available for those who really do.

After trying her PCP’s office try the local senior center if you have one they often have assistance or at least guidance in what programs might be available and where to go to find all of that out. It will be time consuming but probably less so than trying to figure out the websites you mention (your state website might be helpful but could be frustrating too) and maybe well worth it. Good luck!

Wow, I am flummoxed about what is meant by this? First of all, you either get Social Security or you do not get it. Does your MIL get Social Security? Is she a citizen or did she work here in our country?
Then there is Medicare. Is you MIL on Medicare? Does she have supplemental insurance?
If there are no funds one can then apply for Medicaid for hellp?
All of these entities have phone numbers. For all the wait will be long. I averaged on any call to any one of them in the last year about 45 minutes. But they will answer your questions and the website will only add to the confusion; you need to know what you want out of any of those websites.
It is a grave mistake to use your own funds. What will happen when you yourselves are in need?
You are caring for MIL in home. Is the financial end of it the worst part? What are the biggest expenses for you?