How to get a doctor to come to the home?

there are medical services that provide in home care.
Depending on the health of the person you are asking about Hospice will do in home care. Weekly visits from a Nurse and if needed a visit from a doctor or Advance Practice Nurse.
If the person is a Veteran there is a Home Based Medical Care that can be provided.

It will be very hard to find a doctor who will do this. All you can do is call around. The best u may do is a Nurse Practitioner who is overseen by a doctor.

I am in south Florida and use an at home doctor service - that is covered by Medicare.

You could ask a social worker or Council on Aging if there is one in your area.

It has been a godsend. They have bloodwork come to the house - pick up urine samples if needed and an NP comes to see mom once every 4/6 weeks or sooner if she needed them. They fill moms prescriptions and it has worked out really great for us.

Does your mom have a social worker, care manager or someone who oversees her health care?

Have you asked her doctor if s/he has a PA or NP who does home visits?

Have you called the Area Agency on Aging and asked them? (They may also be able to provide case management for your mom).

Lastly, have you googled "doctors who make house calls near (your mom's town)?

It depends on where you live and the availability of doctors, or nurse practitioners. See this recent brief discussion:

https://www.agingcare.com/discussions/fyi-in-home-doctor-care-469617.htm?orderby=recent