can we migrate a .net framework 4.8 web service(asmx) to AWS

Yes, it is possible. However, the approach and effort required will depend on the specific requirements of your web service. For migrating to Lambda, you can use the .NET Core 3.1 runtime, which is supported by AWS Lambda. You can create a Lambda function in .NET 6 or 7 using the .NET Core 3.1 runtime and deploy your web service code as a Lambda function. However, you will need to make sure that any external dependencies that your web service relies on are compatible with the .NET Core 3.1 runtime. For migrating to EKS, you can containerize your web service code and deploy it to an EKS cluster. You can use any .NET runtime that is compatible with Docker to create a container image of your web service. You can then deploy the container to EKS as a pod using Kubernetes. However, you will need to make sure that any external dependencies that your web service relies on are compatible with the .NET runtime that you choose. It is require some extra effort and may be you need to made some changes in the code as well.